Freedom

The novel is a quest novel, where the main characters pursue a specific goal. Will, Henry, and Beanpole quest for the White Mountains not because of their physical geography but because of what the White Mountains represent - freedom.

The two countries in which the characters live, presumably similar to all countries on Earth, are not free. They are based around a feudalistic-type government structure with the strange race of Tripods dominating the top level of the government. All people age fourteen or older are taken by the Tripods and Capped. Once Capped, an individual's thoughts and actions can be, and often are, controlled entirely by the Tripods. Furthermore, the Tripods' goals, motivations, and plans are completely unknown to the humans, who are, in essence, their slaves.

Only humans of age thirteen on younger, considered to be children, are truly free. Only children can have their own thoughts...