The story of The Tripods is a variation on post-apocalyptic literature, wherein humanity has been enslaved by "Tripods": gigantic three-legged walking machines, piloted by unseen alien entities (later identified as "Masters"). Human society is largely pastoral, with few habitations larger than villages, and what little industry exists is conducted under the watchful presence of the Tripods. Lifestyle is reminiscent of the Middle Ages, but small artifacts from the Modern Age are still used, such as watches.
Humans are controlled from the age of 14 by implants called "Caps", which suppress curiosity and creativity. Some people, whose minds are broken by the Caps, become vagrants. According to The City of Gold and Lead, Masters begin to believe that humans should be capped at an earlier age "because some humans, in the year or two before they are Capped, become rebellious and act against the masters."; but this cannot be done because Capping must wait until the braincase has stopped growing.
The White Mountains (1967)
Life goes on largely as it had in the pre-industrial era, excepting that all adult humans are subject to Tripod control. Protagonist Will, a thirteen-year-old boy living in the (fictional) English village of Wherton, is looking forward to the next "Capping Day", until a chance meeting with a mysterious Vagrant named Ozymandias prompts him to discover a world beyond the Tripods' control. He is accompanied by his cousin Henry and a French teenager named Jean-Paul, nicknamed "Beanpole". The novel climaxes with Henry and Beanpole discovering that earlier, unbeknownst to them, Will was captured by a Tripod and implanted with a tracking device, intending to expose the human resistance. When Henry and Beanpole remove the device, a nearby Tripod attacks them; but the boys defeat the Tripod and eventually join the resistance, located in the titular White Mountains (most likely the French Alps).
The City of Gold and Lead (1968)
After a year in the White Mountains, the resistance charges Will, Beanpole, and a German boy, Fritz, to infiltrate a Tripod city by competing in a regional sporting exhibition. Will, a boxer, and Fritz, a runner, win their respective contests, while Beanpole fails to win in the jumping events.
The winners are taken to the Tripod city in a pressurised dome astride a river. Inside the city, the boys discover the Tripods' operators, whom they refer to as the 'Masters'. Human males are slaves inside the cities, while beautiful females are killed and preserved for the Masters to admire. Slaves are furnished with breathing masks to survive the aliens' atmosphere, but are rapidly exhausted by the stronger artificial gravity and must therefore be periodically replaced. Although Fritz is abused by his Master, Will is treated as a pet by his. Eventually, Will's Master reveals a plan to replace the Earth's atmosphere with the Masters' toxic air to enable full control of the Earth. When the Master finds Will's diary, Will kills him to maintain the secret. With the assistance of Beanpole, Will escapes, and they return to the White Mountains. The story's title refers to the gold colour prevalent in the Masters' cities, as well as the leaden weight of the increased gravity on the human slaves.
The Pool of Fire (1968)
Will and Fritz travel to Eastern Europe, the Caucasus, and the Middle East to organize resistance against the Tripods. The resistance, having ambushed a Tripod, discover that alcohol has a strong soporific effect on the Masters, and use this knowledge to simultaneously attack their cities. Having introduced alcohol into the aliens' city water systems, two raiding groups kill the resident aliens; but the initial attack on the last city is unsuccessful and an aerial attack is undertaken using hot-air balloons and a cache of grenades. During this assault, Henry jumps from his balloon onto the city's domed roof and sets off his grenade, killing himself and shattering the dome. The exposure to Earth's atmosphere kills the Masters, and Henry is remembered as a hero. The Masters' spaceship arrives, and they destroy the remains of the cities, presumably to prevent the humans from reverse engineering the Masters' technology and launching a retaliatory expedition. The saga ends with a renewal of nationalist sentiments, with tensions building towards war, which Will and his friends plan to prevent.
When the Tripods Came
When the Tripods Came is a prequel written twenty years after the publication of the original trilogy. The plot follows the description of the conquest given in the second book of the main trilogy. Fearing the technological potential of humanity, the so-called 'Masters', unable to defeat humanity in a conventional war, hypnotise people through a television show called The Trippy Show, later using Caps to control them permanently. As in the original trilogy, the narrator of When the Tripods Came is a young English boy. As society slowly falls under the control of the Masters, he and his family escape to Switzerland, which has mounted the longest-lasting resistance. As the Swiss are themselves enslaved, the narrator and his family establish the "White Mountains" resistance movement of the original trilogy.
Editions have been published by
- Hamish Hamilton (UK First Edition)
- Simon & Schuster (USA First Edition)
- Collier Books
- E. P. Dutton
- Thorndike Press
- Knight Books
- Turtleback Books
- Beaver Books
- Audible Studios (audiobook)
The series has been translated into Finnish, French, German, Hebrew, Persian, Spanish, and Mandarin Chinese (Taiwan).
Multiple graphic adaptations have been produced, notably including:
- Boys' Life, The Boy Scouts of America magazine, serialised all three books in the trilogy from May 1981 to August 1986. Artist Frank Bolle drew the single page black and white proofs which were then inked by another person.
- In 1985, the BBC initiated BEEB, the BBC Junior Television Magazine, and started to present in picture strip form additional adventures of Will, Henry, and Beanpole on their way to the White Mountains, starting at some unspecified point during the fourth episode of the first BBC serial as the trio pass through ruined Paris, and then heading off at a tangent to the television version. From Issue 6, the boys were accompanied on their journey by a young woman named Fizzio, a character original to the strip. The strips were drawn by John M. Burns and in each issue, they consisted of three pages; the first two in colour and the third in black and white. The storyline was never concluded as BEEB ceased publication after only 20 issues.
Series one of The Tripods, broadcast in 1984, which had 13 half-hour episodes written by the well-known author of many radio plays Alick Rowe, covers the first book, The White Mountains; the 12-episode second series (1985) covers The City of Gold and Lead. Although a television script had been written for the third series, it never went into production.
The first series was released on both VHS and DVD. The BBC released Tripods – The Complete Series 1 & 2 on DVD in March 2009.