


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 uncapped man named Ozymandias prompts him to discover a world beyond the Tripods' control. Life goes on largely as it had in the pre-industrial era, excepting that all adult humans are subject to Tripod control. 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 brain-case has stopped growing. Some people, whose minds are broken by the Caps, become vagrants. Humans are controlled from the age of 14 by implants called "Caps", which suppress curiosity and creativity. Lifestyle is reminiscent of the Middle Ages, but small artifacts from the Modern Age are still used, such as watches.

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. 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").
