The 39 Clues
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Linda Sue Park
Margaret Peterson Haddix
|Media type||Print (hardcover)|
The 39 Clues is a series of adventure novels written by a collaboration of authors, including Rick Riordan, Gordon Korman, Peter Lerangis, Jude Watson, Patrick Carman, Linda Sue Park, Margaret Peterson Haddix, Roland Smith, David Baldacci, Jeff Hirsch and Natalie Standiford. The books chronicle the adventures of two siblings, Amy and Dan Cahill, who discover that they belong to the Cahill family, the most influential family in history. The main story arc concerns Dan and Amy's quest to find the 39 Clues, which are ingredients to a serum that can create the most powerful person on Earth. Since the release of the first novel The Maze of Bones on September 9, 2008, the books have gained popularity, positive reception, and commercial success. As of July 2010[update], the book series has about 8.5 million copies in print and has been translated into 24 languages. The major publisher of the books is Scholastic Press in the United States. Steven Spielberg acquired film rights to the series in June 2008, and a film based on the books will be released in 2014. The series also originated tie-in merchandise, including collectible cards and an interactive internet game.
- Amy Cahill and Dan Cahill are the series' protagonists. Grandchildren of Grace Cahill, they became orphans when their parents died in a fire seven years before the events of the first novel. Since then, they have been in the care of their great-aunt Beatrice, before traveling to find the 39 Clues. They both have jade-green eyes, but Amy has reddish-brown hair, while Dan's is a dark blonde; Dan likes to joke around, while Amy is more introverted. However, the cutthroat atmosphere of the hunt causes Dan to become more cynical, a development that plays a larger role in Cahills vs. Vespers. At first, the siblings do not know to which branch they belong. The Viper's Nest reveals that Amy and Dan are part of an unknown fifth branch, the Madrigals, who aim to unite the Cahill family.
- Grace Cahill is the Cahill matriarch, Amy's and Dan's grandmother, and leader of the Madrigal branch. She has traveled all over the world and settled in Attleboro, Massachusetts. The Maze of Bones begins with her death and her last minute change to her will.
- Nellie Gomez is the Cahills' au pair. Of Mexican and French descent, she can fly a plane, drive many types of cars, and speak over ten languages. She unknowingly helps Amy and Dan in the hunt for the 39 Clues, but she later decides to help the children.
- William McIntyre is Grace Cahill's mysterious lawyer, advisor, and "closest confidant for half of her life." In the first book, he advises Cahill siblings to "trust no one" and "beware the Madrigals." He helps an ominous character, the Man In Black, who follows the Cahills on the hunt and whom Storm Warning reveals is Fiske Cahill, Amy and Dan's great-uncle. Luna Amato, who is part of a group that oppose the Cahills called the Vespers, kills McIntyre in A King's Ransom.
Series One: The 39 Clues 
The novels revolve around Amy and Dan Cahill, two orphans who, upon their grandmother's death, discover that they are members of the Cahill family, whose members have shaped the history of their world. The ancestors of the Cahill family are Gideon and Olivia Cahill, whose children created the branches of the family. The branches constantly compete against each other in a hunt for the 39 Clues, ingredients to a serum, the source of the family's power. Amy and Dan, along with their au pair Nellie, enter the hunt for the Clues and become embroiled in the conflict between the Cahill branches. As Amy and Dan participate in the hunt, they unearth secrets about their Cahill ancestors, their parents, and the Madrigals, a mysterious organization. Each book chronicles one location Amy, Dan, and Nellie travel to and focuses on one historical character to which a Clue is linked. The main narrative focuses on Amy and Dan's pursuit of the Clues while evading the sabotage of their competitors, Cahills from other branches. The books also contain the perspectives of the other Cahills as their view of Amy and Dan changes. The environment Riordan and the other authors have created is an alternative reality in which influential historical figures are all part of a single family. The world of The 39 Clues exists in parallel with the real world; other than the Cahills, no one knows the Cahills exist or how much they have shaped the world.
Book 1: The Maze of Bones 
Released September 9, 2008, The Maze of Bones is the first book in the series, written by Rick Riordan. Shortly before her death, Grace Cahill requests that her lawyer, William McIntyre, change her will. At the funeral, McIntyre informs her grandchildren, Dan and Amy, of a choice: one million dollars or a chance to be the greatest Cahill in history and the most powerful people in the world.
Amy and Dan enter the Clue hunt, competing against more experienced Clue hunters: the Holts, Alistair Oh, the Starlings, the Kabras, Jonah Wizard, and Irina Spasky. Pursuing clues hidden in Grace's library and the Franklin Institute, Dan and Amy discover that Benjamin Franklin has hidden a clue in Paris. After convincing their au pair, Nellie, to chaperone their trip, Amy and Dan travel to Paris. While on the journey, Amy and Dan discover the conflict-ridden history of the Cahills that Grace hid from them to protect them. Racing through Paris—above ground and underground—the siblings solves codes and ciphers and find the clue in a vial. The Kabras steal the vial, but Dan solves the puzzle on the envelope they received at the beginning of their hunt and discovers the clue: "iron solute". Amy's Internet searches for Franklin leads them to the probable location of the second Clue: Vienna, Austria, the home of Wolfgang Amadeus Mozart.
Book 2: One False Note 
One False Note is the second book in the series, written by Gordon Korman and released December 2, 2008. After Amy, Dan, and Nellie obtain the first clue, they and the other Cahills travel to Vienna, Austria to find a clue relating to Mozart and his sister, Maria Anna "Nannerl" Mozart. On the train ride to Vienna, the Holts rob Amy, Dan, and Nellie of sheet music, a code that leads to the Clue, forcing them to rely on Dan's photographic memory. They arrive and go to an archive to find Nannerl's diary, only to discover that it has been stolen. They track down the thief, fellow competitor Jonah Wizard, and steal the diary back. The diary leads them to Salzburg, Mozart's birthplace; their search there ends in an explosion. Dan, Amy, and Nellie then go to Venice, where Dan and Amy sneak into a museum. The Kabras attack them and play the harpischord. They trigger a booby trap that knocks them out. Amy and Dan find the second clue, tungsten, and a pair of Japanese swords, a hint for their next destination.
Book 3: The Sword Thief 
The Sword Thief is the third book in the series, written by Peter Lerangis and released March 3, 2009. A pair of swords from Vienna leads Amy, Dan, and Nellie to Japan for a clue related to the Japanese warrior Toyotomi Hideyoshi. Teaming up with Alistair Oh and the Kabras, the three follow a trail of clues to Korea, where they stay at Alistair's house. A book in Alistair's secret library leads them to a mountain called Pukhansan. The group finds an entrance to a cave that hides Hideyoshi's treasure, and the third clue, gold. Dan discovers and decodes an anagram and tricks the Kabras, who escape and seal everyone else in the cave. After escaping, Dan, Amy, and Nellie head for Egypt, as hinted in the anagram.
Book 4: Beyond the Grave 
Beyond the Grave is the fourth book in the series, written by Jude Watson and released June 2, 2009. Dan, Amy, and Nellie search for a clue in Egypt while being pursued by the other Cahills. Theo Cotter, an Egyptian archaelologist, aids them in their quest for the fourth clue. He betrays them, and the siblings and Nellie narrowly escape death. They find the fourth clue, half a gram of myrrh, through a Sakhet statue Grace left them.
Book 5: The Black Circle 
The Black Circle is the fifth book in the series, written by Patrick Carman and released August 11, 2009. After receiving a telegram from "NRR," a mysterious figure, Dan and Amy leave for Russia. Upon arrival, another hint from NRR leads them to a credit card and two false passports belonging to their dead parents. Allying with the Holts, Amy and Dan infiltrate a Lucian stronghold. It is revealed that the clue is amber.
Book 6: In Too Deep 
In Too Deep is the sixth book in the series, written by Jude Watson, who wrote Beyond the Grave. It was released November 3, 2009. Dan and Amy head to Sydney, Australia to learn about what their parents knew about the 39 Clues from their dad's cousin, Shepard Trent. They discover that Ian and Natalie's mother, Isabel Kabra, has joined the hunt. Isabel hunts the two down to kill them, but the siblings escape and follow a clue to Krakatau (the ring of fire), where they meet Alistair. Isabel sets fire to their hut. Irina Spasky dies while saving Amy, Dan and Alistair. After the fire, the three look in Irina's bag and find song lyrics, revealing the clue, water. At the end of the book, they suspect that Nellie spies on them for someone else.
Book 7: The Viper's Nest 
The Viper's Nest is the seventh book in the series, written by Peter Lerangis and released February 2, 2010. The morning after the fire that killed Irina Spasky, Dan and Amy discover that Irina's last words are actually a song, which points them to their next destination: Pretoria, South Africa. They infiltrate a Tomas stronghold, and the Holts chase them. As Dan and Amy leave South Africa, the Kabras capture them. Flying Grace's old plane The Flying Lemur, the siblings escape with a vial of green liquid. During a quarrel, the vial breaks, and the green liquid, a Kabra poison, spills onto Dan's arm. To save Dan, they fly to Grace Cahill's home in Madagascar, where they find out that the clue is aloe and their parents were Madrigals, an organization Amy and Dan have learned to fear, therefore meaning that they themselves are Madrigals.
Book 8: The Emperor's Code 
The Emperor's Code is the eighth book in the series, written by Gordon Korman. It was released April 6, 2010 Amy and Dan go to China to find the next clue. They split up following an argument but reunite at Mount Everest, where they find a Janus vial left by British Cahill mountaineer, George Mallory. They battle Eisenhower Holt and Ian Kabra over the serum. Ian falls, and Amy sacrifices the Janus serum to save Ian.
When Dan thinks they have lost the clue, Amy shows him the poem on the piece silk fabric they found in Beijing and tells him the next clue is raw silkworm secretion. They also realize that a formula on the silk means that all the serum of the branches add up to one master serum. Dan shows Amy the locket he found at a Shaolin temple, which contains an inscription of the name of the pirate Anne Bonnie. They decide their next destination is the Caribbean.
Book 9: Storm Warning 
Storm Warning, by Linda Sue Park, was released May 25, 2010. Amy and Dan continue their hunt in the Bahamas and Jamaica. They distrust Nellie after discovering that she worked for William McIntyre. After that, they head out to the Port Royal excavation site with Lester, Miss Alice's grandson, and find a box Grace donated that can fit the objects they collected: the Ekat dragon necklace, the Lucian snake nose-ring, the Janus Wolf Fang, and the Tomas Bear Claw. However, they cannot open the box, and after a non-Cahill ally dies, the siblings decide to quit the hunt and return to their Aunt Beatrice. However, instead of driving them to the airport, Nellie stops at Moore town, and gives the box to the Man In Black, an ominous figure who has been following Dan and Amy. The Man In Black gives the siblings one hour to open the box. As he walks away, he says that in the game all sides are one and all are needed to survive. After many tries, they figure out that on the strip they found is an unfolded möbius strip. Amy inserts the strip to the final slit and the box springs open. It contains a poem by Madeleine Cahill, and the clue, Mace.
The Man In Black reveals his true identity as Fiske Cahill, Amy and Dan's great-uncle and Grace's younger brother, and tells them about Madeleine Cahill and the Madrigal branch, as well as granting the two active Madrigal status. He then also gives Nellie active Madrigal status even though she is not a Cahill. After reading the poem, Dan concludes the siblings' next stop is England. There, they must finish the clue hunt and stop the other branches from fighting, as per their new status as active Madrigals.
Book 10: Into The Gauntlet 
Into The Gauntlet, the penultimate book in the first series, was released August 31, 2010, written by Margaret Peterson Haddix. All the teams arrive on the founder, Gideon Cahill's home on an island. Isabel Kabra captures them and forces each of them to say their clues, by threatening to kill their loved ones. Amy smashes the serum over Isabel's head, knocking her out. Amy and Dan are left with a list of everyone's clues in their hands, which each team gives them, "Because they don't trust themselves around the serum, and the great power it wields."
Book 11: Vespers Rising 
Vespers Rising serves as a transition between the first and second series. It was written by Rick Riordan, Peter Lerangis, Gordon Korman, and Jude Watson. The book was released April 5, 2011. This book has four plot lines. The first describes Gideon's discovery of the master serum and betrayal by his friend and the first Vesper, Damien Vesper. The second recounts Madeleine Cahill's life and her attempt to reunite the Cahill family, protect her father's ring, and outwit Daimen Vesper in acquiring it. The third tells of Grace's first mission to Casablanca, as she competes against Vesper agent General George S. Patton to retrieve Gideon's gold ring. The fourth describes Amy and Dan's retrieval of Gideon's ring that Grace bequeathed to Amy, while escaping from Casper Wyoming, a Vesper agent who is after it.
Series Two: Cahills vs. Vespers 
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Book 1: The Medusa Plot 
Two years after the Clue Hunt, all who succeeded in finding Gideon's serum recipe have become Madrigals. The feud between the Cahill branches has ended, and the family unites to battle a new enemy: the Vespers. The Vespers are a secret organization led by Vesper One. They have been the Cahills' enemies since the time of Gideon Cahill. The Vespers hold seven Cahills hostage to coerce Amy and Dan into retrieving rare artifacts for them.
The book begins when Vespers kidnap seven Cahills. Shortly after, three Vespers attack Dan and Amy on a school bus and try to kidnap them, but Dan and Amy fight them off. Right after the attack, Detective Corelli arrives and takes them home, advising them to hire bodyguards. At the mansion, McIntyre informs them of the kidnapping, and Vesper One orders them to go to Florence by the next morning or one of the hostages dies.
Sinead, McIntyre and Ian, who has arrived from London, remain in the Cahill Command Center to research the Vespers and the possible whereabouts of the Cahill hostages, while Dan and Amy go to Florence, where a message tells them to steal Caravaggio's "Medusa" in the Uffizi gallery. Jonah Wizard and Hamilton Holt help them steal the picture, but when they give the painting to the Vespers, it is a fake. Vesper One sends them a video of Nellie getting shot in the shoulder.
Amy, Dan, Hamilton and Jonah discover that decades ago, a Mud Angel named Tobin stole the real painting. They steal the painting from him but lose the chargers for the DeOssie phone while escaping. When Ian then goes out to look for info on the phone, he runs into Evan, who immediately recognizes it. Ian tells Evan about the Cahills and invites him to join the Command Center.
Upon further investigation of the painting, the siblings find Latin words on the back of the painting, prompting Dan to ask his friend, Atticus, for help. Atticus then tells Dan to come to the Colosseum, where Dan finds out that the snakes in Caravaggio's Medusa is a map of the Colosseum, with the one spot where two snakes bite each other as the "X". In the tunnels, they found DaVinci's Medusa shield, on which Caravaggio based his picture, and the original copy of Marco Polo's book, Il Millione (The Million), which the Vespers are looking for. After an argument with the Rosenblooms, the siblings steal the book and flee.
Jonah, Hamilton, Ian and Sinead find the DeOssie factory and sneak in. After searching the whole factory, they find the chargers but not the hostages. On the way out, Hamilton triggers a trap by shaking a vending machine, which blows up the entire factory.
Dan and Amy go to a circus to give Vesper One the real painting. A circus acrobat working for Vesper One steals the painting before a blackout. As everyone leaves the building, Dan and Amy see the acrobat dying on the sidewalk. After asking the acrobat whom she works for, she replies, "Bruciato", or burned, referring to Vesper One's burned arm. Outside the circus, they receive another text message from Vesper One, telling them to go to Lucerne, Switzerland.
Book 2: A King's Ransom 
Amy and Dan are wandering in Santa Maria Novella train station in Florence when they come across a girl named Vanessa Mallory, who is Cheyenne Wyoming in disguise, and use her as a distraction to get into the train for Lucerne, Switzerland where Vesper One is sending them for their next mission: find the de Virga map. Once on the train, the siblings realize that they have been tricked, and an Interpol agent named Milos Vanek tries to hunt them down. They escape the train by hiding inside luggage bags and disembark at Enderberg.
They disguise themselves as rich heirs to enter an auction house in Lucerne. They sneak into the office and retrieve the de Virga Map archives written in German. Ian translates it, revealing that four people, Otto Hummer the professor, Jane Sperling the socialite, Marcel Maubert the art dealer, and Reginald Tawnley the person who owned a private library, have something to do with the map. Unfortunately, the report about Amy and Dan's criminal heists have reached the auction house, but they escape by creating diversions.
Later, William McIntyre meets Amy and Dan inside a Blue Sedan, gives them a GPS wrist watch, and drops them off at a safe house in Basel. Sinead and Evan share the information about the four listed in the archives: Maubert and Tawnley died in war, Hummel worked in the Nazi party, and Jane was a Jew whom the Cahills believe tried to protect the de Virga map, which was owned by a Jewish family.
Dan gathers ingredients to create the Master Serum, which he intends use as backup. Using the information the center gathered, Amy concludes that they have to search Neuschwanstein Castle.
After calling for backup, Jonah and Hamilton both come to Munich on their way to the castle but accidentally pick up Cheyenne Wyoming, who nearly kill them. Amy and Dan find a black notebook owned by Sparrow, a.k.a. Jane Sperling at the castle. Inside is a note that leads to the de Virga map. By another stroke of bad luck, Casper bumps into them and almost kills them, but Jonah and Hamilton rescue them.
Analysis comes from the Command Center about the notes: they are about a Johannes Kepler book that was recovered from the castle to the Library of Philosophy and Cosmology in Prague, Czech Republic. They head there to investigate the book but cannot without a reference. They try to use Rosenbloom's father but fails. At the hotel, they again escape from Milos Vanek.
After going to Sedlec Ossuary on a hunch from the Command Center, they discover a flash drive file about a Vesper One report and the initials AJT, Arthur Josiah Trent, carved on the wall, which shocks Dan because Arthur was their father. They then call Erasmus, who answers all their questions about Arthur. He explains how Arthur was initiated into the Vespers but later cut off all ties with them. Afterwards, Ian calls to tell Amy that a Lucian professor has agreed to help Dan and Amy enter the Library of Philosophy.
After going to the library, they bump into Jake and Atticus outside. Although Jake is originally inclined to call the Interpol, Atticus urges him to wait upon seeing the picture of Jane Sperling, who is his great grandmother. Atticus and Jake both decide to help the siblings. Inside, Katja Mavel, the director of the library, gives them what they want. Jake succeed in luring her away, and that leaves Dan, Amy, and Atticus. They finally find the map inside the book itself.
In Rome, a Vesper dressed like a waiter kills William, who leaves a secret message in his shoe before he dies.
Back in Prague, Amy and Dan tell Atticus what they are doing, and Atticus reveals his involvement as a Guardian. The siblings have never heard of the group. Dan connects Il Milione and the map to Samarkand, Uzbekistan - their next destination. Vesper One asks them to drop off the package at the Astronomical Tower, near the statue of Jan Hus. They do what is asked, but it goes wrong. Atticus follows them and is kidnapped.
Vesper One now knows Dan and Amy have been hiding Marco Polo's epilogue all this time and explains that Atticus was the price of keeping it from him. Minutes later, another message is sent to Dan's phone, apparently from AJT.
Book 3: The Dead of Night 
The third book, The Dead of Night, is written by Peter Lerangis and was released March 6, 2012. The Vespers have Atticus Rosenbloom, Dan's only friend. Unless Dan and Amy comply with the Vespers' demands, Atticus will die. Vesper One asks Amy and Dan to find a stale orb, which the siblings discover is an anagram for astrolabe. They fly to Samarkand, Ubekistan to find the astrolabe and deliver it to Vesper One. Atticus escapes, and Dan suspects his father murdered William McIntyre and is Vesper One. Ian goes off alone to New York, suspecting Isabel to be Vesper One, and Isabel manipulates him into staying by saying that the other Cahills are not his friends and only tolerate him. The hostages are rumored to be in Argentina because of a lizard Nellie holds in a photo.
Dan has gathered seventeen ingredients of the thirty-nine for his own master serum. Amy worries that Dan is growing up too fast. Dan has also been receiving texts from a Vesper claiming to be his father, so he texts back a question to confirm this and is shocked that the answer is correct. The book reveals Vesper 4 to be weatherman Sandy Bancroft.
Book 4: Shatterproof 
Shatterproof, written by Roland Smith, was released September 4, 2012. Among Interpol's most wanted, Amy and Dan must comply with Vesper One's demands to steal the Golden Jubilee diamond displayed at Berlin's Pergamon Museum to keep Vesper One from killing a Cahill. The Diamond is too well protected, and they escape from security. Vesper One reveals that they were merely a distraction, and he has the things he needs. He tells them to find the "Apology", a Roman article written by a soldier who apologizes for attacking the Africans. Jonah, Hamilton, and Erasmus work on tracking down Luna Amato, so she can tell them the reasons and people behind William McIntyre's murder. Luna kills Erasmus, but Jonah kills her. The hostages try to escape, but the Vespers stop them. Phoenix falls off a cliff but survives. Before they escape, Casper and Cheyenne inform Amy and Dan of Phoenix's supposed death. Vesper Three is revealed to be Sinead Starling, who frames Ian.
Book 5: Trust No One 
Trust No One is by Linda Sue Park, the author of Storm Warning and was released December 4, 2012. The novel features Isabel and takes place in Brazil. Vesper One tells Amy and Dan to go to Yale and steal the Voynich Manuscript, Folio 74. Evan finds out Sinead is Vesper Three, but she has already left. She blocks Evan's messages, but Amy finds out and the two fight each other. Sinead pulls out a tiny gun and shoots, but the bullet only grazes Amy's neck. When Jake arrives, Sinead flees.
Amy then apologizes to Ian. They head off to Yale and find Dr. James, the Rosenblooms' mother's friend. They find that the folio is missing. After meeting Dave Speminer (another friend of Rosenblooms' mother, Astrid), Atticus remember something that his mom said to him before dying: Missing Voynich with LaCher. After Dave leaves, Vesper One streams a live video of Nellie, telling them of Alistair's death. They check Astrid Rosenbloom's e-mail for any clues about the folio's location and find a coded email to Astrid which directs them to the Iguazu Falls in Brazil. During a capoeira performance, a capoeirista "accidentally" injures Atticus. At the Falls, a second attack occurs, and a blow dart coated with curare meant to hit Atticus hits Dan instead. A doctor nearby saves Dan from the poison. They realize Isabel Kabra orchestrated the attacks, and that there will be one more, when Amy remembers that the capoeirista told her: Um, dois, tres (One, two, three in Portuguese), and Amor to the littlest, from Isabel.
A taxi driver takes them to Mabu Thermas Hotel and Spa and sees Dan's new wallpaper on his laptop, one of the "plumbing pictures" in the Voynich. At the spa, they meet LaCher Siffright who has Folio 74. They meet for lunch at the hotel, where LaCher protects Atticus from the third attack: a man acting as a waiter who threw a knife and a skewer at Atticus. LaCher took the knife to her neck and was taken to a hospital. She tells Dan "You know... You know," before fainting. They find the folio and realize that Archimedes plays a part in the Vespers' master plan. They suspect Isabel to be Vesper One and ask Hamilton and Jonah to find out more about Archimedes at Syracuse. Before Dan and Amy go to the drop off, a video on the DeOssie phone shows a gun at Nellie's temple and the trigger twitching, before being abruptly cut off. Amy is tricked into giving Vesper One the Madrigal ring or Gideon's ring, which Grace entrusted her with. Dan and Amy drop off the folio at Strawberry Fields, together with the last item Vesper One wanted, Gideon's Ring.
After that, they found out the Vespers' master plan: The Vespers wanted to use the things they stole - the Astrolabe, the Book of Ingenious Devices, the "Apology", strong electromagnets, a replica of the Antikythera Mechanism, an armillary sphere (The Marco Polo Heist), Magellan's gear (The Magellan Heist) and Gideon's Ring - to build the Machina Fini Mundi, a doomsday device using the electromagnets on subduction zones to create natural disasters like earthquakes, tsunamis and volcanic eruptions. Traumatized, Amy hides in her own mind, blocking out the real world. Dan decides that the team should go to Attleboro and Evan, having been contacted by Dan, says he wanted to talk to Amy, but Dan tells him that she is in no condition to do so.
Dan realizes that to combat a doomsday device he would need the serum which he had recently created without Amy's or the Rosenblooms' knowledge. Dan drinks an unknown liquid an Ekat scientist at the Columbia Chemistry Laboratory manufactures.
Book 6: Day of Doom 
The final book is by David Baldacci and was released March 5, 2013. Starting from the last chapter of Trust No One, Dan drinks the "serum" that he made with the help of an Ekaterina scientist. Amy had known that Dan was creating the serum and replaced the real serum with a mixture of vegetables. Dan angrily says that he was willing to die to save the world. Amy tells Dan that Isabel Kabra is Vesper Two, not Vesper One, and that they hacked into her flight plans and found out that Isabel is flying to Washington D.C.
Following a clue from Atticus' mother, Amy and Dan go to the National Museum of Natural History, which houses the largest collection of Lewis and Clark items. On the train, Vesper One sends them a video of the hostages. Atticus realizes that Ted is blinking Morse code and decodes the message: Riley McGrath is Vesper One. At the museum, they find out that Isabel wanted to see Lewis and Clark's compass. Dr. Nancy Gwinn, a Lewis and Clark expert, takes the four to see the Lewis and Clark compass. Upon examining it, Dan realizes numbers and letters are scratched onto the back. When they exit the museum, Isabel and her men arrive. They split up, and Amy chases after Isabel. Isabel tricks and shoots her, but Dan saves Amy.
Evan and Ian receive a call from Phoenix from a motel in Washington state and head there with Hamilton and Jonah, whom Sandy, Casper, and Cheyenne follow. Disguised as a waitress, Cheyenne walks up and forces them into the back of a van, taking them to the Rocky Mountains. Casper takes Ian out of the truck and takes him to video chat with his mom. Isabel asks Ian to kill one of the hostages by claiming Vikram poisoned her and she is dying. Ian pretends to believe her. While doing Isabel a favor by meeting his sister, Vesper One asks what is Ian doing here. Ian feeds him lies about Isabel, Sandy, Casper, and Cheyenne plotting against him. Vesper One believes him, and as a "favor", gives Ian a choice to kill Fiske, Ted or Natalie. Ian stalls for time, saying that he has not made up his mind.
Dan decides to take a train to the Cascade Mountain Range, where they believe the hostages and the Machina Fini Mundi are. During the night, Atticus grows suspicious of Dave, who was in the perfect position to kill his mother. He finds out that Dave Speminer is an anagram of Damien Vesper, the founder of the Vespers. Dan finds out that Isabel had been posing as his father and sending the text messages. Isabel kidnaps Atticus, steals the serum that is in Dan's bag, stops the train, and escapes. Dan, wearing the night vision goggles he takes from one of Isabel's men, discovers that Isabel has modified the coordinates etched on the compass's reverse. The location of the hostages and the Machina Fini Mundi turn out to be on the Rocky Mountains, where the train stopped.
The Vespers move the hostages, Ian, Evan, Jonah, and Hamilton from the Cascades to the Rockies. En route, the hostages break free and incapacitate Sandy, Casper, and Cheyenne and meet up with Amy, Dan, Atticus, and Jake. They find the Machina Fini Mundi and battle the Vespers. The Vespers fatally shoot Evan, while the device electrocutes Natalie. The remaining Cahills decide to protect the Machina Fini Mundi from Vesper One.
Amy turns the Machina Fini Mundi into a giant electromagnet. When the Vespers come, the device disarms and electrocutes them. Sandy and Damien arrive and hand out stone weapons. Isabel, seeking revenge for her children and having drunk Dan's serum, arrives and tries to stop Damien from inserting the final piece. The device activates, but Isabel destroys it. Damien melts into the device, causing a malfunction and explosion, which kills Damien and Isabel Kabra. A falling rock knocks Amy unconscious, Jake carries her out, and she wakes up after seven days. She and Dan then discuss how they would return to their normal lives.
Series Three: Unstoppable 
The third series, Unstoppable, was revealed in Publishers Weekly on 25 October 2012. Nowhere to Run, the first book in the series, will be released October 1, 2013. Jude Watson wrote the story arc for this series and Cahills vs. Vespers.
Supplementary works 
Scholastic has expanded the 39 Clues universe with several books. In 2010, Scholastic published Agent Handbook, which explores the techniques that the clue hunters in the series use to find clues, and The Black Book of Buried Secrets, which provides more information about events in the series. On the last week of December 2011, the Scholastic editorial team released seven short stories as part of The 39 Clues: Rapid Fire e-book series. The editorial team has also released The Cahill Files, which inclues Operation Trinity, Spymasters, and three e-books. As part of the multimedia interactive experience to promote the series, Scholastic includes six cards in each book of the 39 Clues series. Each card unlocks one online clue, which readers can unlock by entering the code on the cards on their 39 Clues account online.
The 39 Clues series consists of adventure novels; however, the novels also fall within the genre of historical fiction. The stories switch back and forth between different characters' points of view. Each novel focuses on one historical figure and geographical location as Dan and Amy explore a clue related to a prominent Cahill family member in an exotic location.
One theme of the series is the relationship between talent and success. Each branch of the Cahill family has specific talents in a certain area; for example, the Ekaterina branch specializes in inventions and technology. Amy and Dan's competitors' talents give them an advantage, yet Amy and Dan consistently are ahead in the hunt and are viewed as the main threats. Over the course of the books, Amy and Dan discover their own talents.
An editorial team in Scholastic came up with idea of an interactive series with online games and asked Rick Riordan to write the first book. Riordan agreed because he thought it was a good idea, and as a middle school teacher, he loved making history enjoyable for younger readers. The project was kept secret for about two years.
As of June 11, 2010, The 39 Clues series has been on the New York Times bestseller list of Children's Series books for 48 weeks. Books in the series have also appeared on the USA Today, Publishers Weekly, and Wall Street Journal bestseller lists.
Critical reception 
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Steven Spielberg acquired film rights to the series in June 2008. Spielberg and Scholastic Media president Deborah Forte will produce the series, while Brett Ratner expressed interest in directing the first film. Screenwriter Jeff Nathanson was hired to write the script in September 2008. In May 2012, Shawn Levy, the director of the Night at the Museum movies, acquired the rights to direct the movie. The movie, The 39 Clues: The Movie, is going to be released in 2014. Universal Studios will release the film, jointly financed by Universal, DreamWorks Studios, and Walden Media, in North America. DreamWorks, through Disney's Touchstone Pictures division, will handle international distribution.
- Riordan, Rick (September 9, 2008). The Maze of Bones. Scholastic. p. 23. ISBN 978-0-545-06039-4. OCLC 192081902. "If you accept, you shall be given the first of thirty-nine clues. These clues will lead you to a secret, which, should you find it, will make you the most powerful, influential human beings on the planet."
- Lodge, Sally (July 22, 2010). "The Success and Grand Finale of The 39 Clues". Publishers Weekly. Retrieved April 29, 2012.
- Yin, Maryann (September 23, 2010). "David Baldacci Joins Several Authors to Write the 2nd Wave of '39 Clues' series". GalleyCat. Retrieved February 11, 2011.
- Smith, Roland. "The 39 Clues Message Board: Book 4 Cover Reveal". Scholastic Inc. Retrieved February 24, 2012.
- Linda Sue Park (2012-07-12). "Book 5 Cover Reveal!". Scholastic, 39 Clues Message Board. Retrieved 2012-07-15.
- Sneak peek at Book 5 of Cahills vs. Vespers Linda Sue Park on Twitter. 2012-06-13. Retrieved 2012-07-15.
- Fuentes, Catherine (September 22, 2010). "'39 Clues' exclusive: New series from Scholastic will feature David Baldacci". Entertainment Weekly. Retrieved October 23, 2010.
- "The 39 Clues Online Press Kit". Scholastic Media Room. Scholastic.
- Jordan, Tina (April 5, 2010). "'The 39 Clues': Exclusive on final two titles, covers!". Entertainment Weekly. Retrieved February 11, 2011.
- Minzesheimer, Bob (November 11, 2011). "Scholastic to publish '39 Clues'-inspired e-book stories". USA Today. Retrieved April 29, 2012.
- Sekeres, Diane Carver; Christopher Watson (June 4, 2011). "New Literacies and Multimediacy: The Immersive Universe of The 39 Clues". Children's Literature in Education 42 (3): 256–273. doi:10.1007/s10583-011-9133-4. Retrieved April 23, 2012.
- Culham, Ruth. "Decoding Writing with The 39 Clues". Scholastic. Retrieved April 29, 2012. "The 39 Clues story is narrated from several different characters’ points of view."
- Stockwell, Laura. "Curriculum Guide for The 39 Clues series". Retrieved 2010-06-09.
- "Rick Riordan Author of the Month Transcript". Scholastic. Retrieved April 29, 2012. "Scholastic came to me with the basic idea and I thought it sounded cool. I like history, puzzles, and games, so the 39 Clues seemed like a perfect thing to write."
- "Rick Riordan Interview". Scholastic. July 2008. Retrieved April 29, 2012.
- Staskiewicz, Keith (August 30, 2010). "'The 39 Clues' round-robin interview". Entertainment Weekly. Retrieved April 29, 2012.
- Karen W. (September 9, 2008). "Rick Riordan in the House! (Part 1)". Ink Splot 26. Retrieved April 29, 2012. "for two years, no one on the team was allowed to say anything about the project to anyone."
- "Children's Books". The New York Times. June 11, 2010. Retrieved June 13, 2010.
- Michael Fleming (June 24, 2008). "Steven Spielberg follows '39 Clues'". Variety. Retrieved September 3, 2008.
- Tatiana Siegel (September 2, 2008). "Jeff Nathanson to write '39 Clues'". Variety. Retrieved September 3, 2008.
- Trumbore, Dave (May 10, 2012). "Shawn Levy to Direct Adventure Novel Series Adaptation The 39 Clues for DreamWorks". Collider.com. Retrieved June 2, 2012.
- Eleanor Barkhorn (July 18, 2011). "The Next Harry Potters: Where Are They Now?". The Atlantic. Retrieved September 2, 2011.
- The 39 Clues (official page)
- 39 – Various – A wiki devoted to The 39 Clues
- Scholastic Plans to Put Its Branding Iron on a Successor to Harry Potter
- The 39 Clues Wiki