Swarm is set in the Praulac Nebula, which is inhabited by a strange insectoid race called the Clagnor. Negotiations between humans and the Clagnor have failed, leading to an all-out war between the two races. The story follows Rawl Mastesen, a prison convict given the task of fighting the Clagnor for a year. After this, if by any chance he survives, his name will be cleared unless he takes an offer for another year on the job for twice the pay.