Things at the Plas Mawr Adventure Centre in North Wales are not going well. Warden Charles Martin has an unfaithful wife, Bett, who has driven him to drink. Jim Lithgow and Nell Harvey are both instructors and appear to be having an affair—and Lithgow is married; Bett, it seems, is also having an affair with another married instructor, Rowland Hughes; and supervision of the boys when they are out in the hills seems most inadequate. And then Bett is found dead in her husband's crashed Jaguar, which she could barely drive. Developments show that what is at first assumed to be accident or suicide, is in fact a murder case. Miss Pink puts two and two together and realises that the school is being used as a cover for something more serious than a few love affairs...