|Publisher||Orion Books Limited|
|Media type||Print (Hardback)|
|Preceded by||Dexter is Delicious|
|Followed by||Dexter's Final Cut|
Double Dexter is the sixth novel written by Jeff Lindsay, and the sixth book in the 'Dexter Morgan' book series about a serial killer who targets serial killers. The book was released on October 18, 2011.
The book begins with Dexter dismembering a pedophile, witnessed by someone who flees in a Honda with distinctive body damage. Dexter begins to spend his evenings hunting for such a car. His wife Rita suspects an affair, and she starts drinking wine.
Meanwhile, a police detective is found dead in his car, every bone in his body broken. Dexter's sister Deborah, also a detective, begs Dexter to help her solve the case; but the only clue is a piece of a taco wrapper, from one of Miami's many food trucks. Soon afterward another police officer, killed in the same way, is found by a fountain near the beach.
Deborah eventually has a stroke of luck and captures the cop-killer. The resulting publicity spills over onto Dexter; his name and picture appear in the press for the first time, and the witness recognizes him.
The witness tells Dexter by e-mail that he knows enough about Dexter to destroy him. Dexter studies his blog, "Shadowblog", without finding any clues other than his ex-wife's initial, A. Dexter begins to think of his antagonist as the Shadow.
Dexter eventually finds the Honda belonging to Alissa Elan, the Shadow's ex-wife. He returns at night but finds that the Shadow – Bernard Elan – has anticipated his visit, mutilated Alissa in imitation of Dexter's style, and called police when Dexter arrived. Dexter narrowly escapes. Bernard, a skilled computer hacker, alters relevant databases to indicate that he died two years ago.
Camilla Figg, Dexter's coworker, is found beaten to death, casting doubt on Deborah's arrest. Dexter notices differences from the cop-killings, but Hood, the detective in charge, ignores him. It emerges that Camilla had hundreds of photographs of Dexter; he, with his imperfect understanding of human emotions, was the only person in Miami Metro Homicide unaware of her crush on him. Hood makes Dexter the prime suspect.
Another message from the Shadow confirms that he killed Camilla. Dexter eventually learns that he is now using the name Doug Crowley, but cannot kill him because of Hood's surveillance, so he asks his brother Brian to do so; but Brian mistakenly kills the real Doug Crowley — for which the Shadow expresses gratitude.
Dexter and family take a trip to Key West, where Rita attends an auction of foreclosed houses. Hood and the Shadow both follow. The Shadow kills Hood and leaves him in Dexter's hotel suite. He then takes Astor and Cody to Garden Key, where he means to set a trap for Dexter, but Dexter reaches the island first. The Shadow, carrying Astor, flees to a boat, which Dexter barely reaches. Astor and Dexter eventually subdue the Shadow, tossing him overboard, and he is killed by a shark.
Deborah meets Dexter back in Key West, and everything is restored to order.