John Christopher's "Tripod Trilogy" is one of the most popular science fiction series ever written for young readers. In addition to receiving a number of awards, it has been translated into many languages and was the basis for a British and American television series. When the Tripods Came, a "prequel" to the trilogy, answers questions posed by the series about the original takeover of Earth by aliens. The book chronicles an invasion by "tripods," giant machines with three legs manipulated by aliens. These aliens use mind control, first through a television program called "The Trippy Show" and, later, through metal caps, to enslave humanity.

As in the trilogy, a few lone humans fight against the aliens, trying to keep their individuality and freedom. The novel, which is narrated by thirteen-year-old Laurie Corday, has immediacy and believability created by a first-person narrator. The novel is filled with suspense created by a number of close calls between Laurie and his family and the tripods and their human servants. While the novel does not resolve the conflicts created by the alien landing, it is full of hope that humans will continue to fight for freedom and looks forward to the trilogy, in which a group of teenagers eventually destroy their captors.

(The entire section is 208 words.)