Case with ropes and rings

The Coroner's Jury found that the boy hanged in the school gymnasium had killed himself, but Sgt. 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 are not to Townsend's liking, as they entail endless games of darts and beer all around in the local pub. Then there is another remarkably similar murder which ocurs elsewhere and Beef bestirs himself to uncover the guilty.