In 2120 AD, the barren surface of the moon is the only home that three generations of earth's survivors have ever kwn. Towns, called Daroks, protect inhabitants from the extreme lunar temperatures. But life is harsh. Hank Havard, a young scientist, is secretly perfecting SH33, a drug that eliminates the body's need for water. When his First Quadrant laboratory is attacked, Hank saves his research onto a memory card and runs from the enemy. Aided by Will, his teenaged nephew, and Maddie, Will's computer-wizard classmate, Hank must conceal SH33 from the dreaded Fourth Quadrant. But suddenly Will's life is in danger. Who can Hank trust-and is the enemy really closer to home?