During their last adventure, Zak Nine and Erro found a mapping device in a crashed prison ship. Following the map, the boys make their way to the Plateau of Leng, a vast desert on Planet Alcatraz. Other than an occasional giant scorpion, the boys seem to be safe on the endless sands until they spring a deadly trap! Huge rocky walls spring up from beneath the sand, grinding against each other and forming into walls, passageways and stone cages. Will the boys be fast enough to avoid getting trapped forever on this hot, desert plain? This special Express edition has a reduced level text of ATOS 2.0 or lower. With exciting illustrations and gripping, page-turning text, it is sure to engross even the most reluctant of readers.