The coroner's jury found that the boy hanged in the school gymnasium had killed himself, but Sergeant Beef disagrees. He takes a job as a temporary school caretaker, abetted by the reluctant Townsend, Beef's biographer, whose brother is a master at the school. Beef's methods entail endless games of darts and beer all around in the local pub, much to Townsend's dismay of course. But when another remarkably similar murder occurs elsewhere, Beef bestirs himself to uncover the guilty.