Will and Henry Parker are thirteen-year-old cousins living in a small English town in the far future. Technology is largely forgotten and humanity lives under a feudal system of government. Humanity has been conquered by a race of beings known as Tripods. Tripods are huge, mechanical beings, perhaps sixty feet tall, with three mechanical legs and metallic tentacles that descend from a hemispherical body. When a person reaches the age of fourteen, they are taken by a Tripod and Capped. Capping is a type of surgical procedure where a metallic mesh Cap is implanted onto a person's head. Once Capped, a person's thoughts and actions are controlled by the Tripods.

Will and Henry learn of a distant location in the South, called the White Mountains, where men live free from the Tripods. The Tripods apparently do not enter the White Mountains, because of the altitude. Will...