Doctor Wignall, the Headmaster of the venerable boys' public school of St. Marks, was proud of the school's traditions. But his confidence was considerably shaken when the young daughter of one of his teachers is brutally murdered in the nearby woods. And the following term brings a series of disturbing revelations when John Prenderby, the charismatic master of North House, uncovers a sordid undercurrent of gambling, blackmail and immorality amongst the pupils, culminating in the murder of one of them. When one of the teachers goes on the run, the police think they are trailing the murderer-but are they?