David is nearly 16, the son of two scientists of the seeding-colony on Hope, orbiting Alpha-Centauri in the Centauri binary-star system. Life is hard; they have little technology except Fred, the ship’s computer, who controls the colonists’ lives in their secure, moated compound, together with his little sock-eating dusting-robots called ‘snufflers’. David has a tentative sexual encounter with his friend Peter, and is shocked when Peter later goes missing …