Southern California - sunny days, blue skies, neighbours on flying bicycles ... ghostly submarines ... mermen off the Catalina coast ... and a vast underground sea stretching from the Pacific Ocean to the Inland Empire where Chinese junks ply an illicit trade and enormous creatures from ages past still survive. It is a place of wonder ... and dark conspiracies. A place rife with adventure - if one knows where to look for it. Two such seekers are the teenagers Jim Hastings and his friend, Giles Peach. Giles was born with a wonderful set of gills along his neck and insatiable appetite for reading. Drawing inspiration from the novels of Edgar Rice Burroughs, Giles is determined to build a Digging Leviathan. Will he reach the center of the earth? or destroy it in the process?