The man called Twelve is a hired gun, taking his laser pistol from planet to planet, hiring his services out to the highest bidder. He finds himself on Glycon-Prime, a new colony at the edge of space. On the hunt for work, Twelve blows into a small, frontier town only to find a massacre. The only survivors? A trio of young children, devastated by the murder of their families and hellbent on hiring the gunslinger to help them get revenge on the leader of the vicious mutants responsible, the man known only as "The Serpent's Head."