They go on a journey to an old and abandoned base, where they find the diary of Andrew Thurgood, a missing early lunar settler.

The diary contains coordinates to a place Thurgood claimed he saw something that looked like a huge flower, and the boys decide to go there and do some investigating themselves.

They crash through the Moon's surface into a series of caverns containing fluorescent plants, many of them able to move, which is a part of and controlled by a single intelligent alien life form.

The novel's main theme is that of the development of a young person's will and independence, and the conflict between benevolent authority and individual conscience.

A film adaptation of the book was in development in 2007, from Walden Media, to be written by Brian Klugman and Lee Sternthal and directed by Rpin Suwannath.