An English rose garden on a summer's day. A small boy watches with interest as his great-aunt cuts the deadheads off the rosebushes with a sharp knife. What could be more peaceful, more harmless? Young Patrick grows up to be a calm, pleasant man, with a good job, a wife and two children, and the best rose garden for miles around. When somebody tells the police that Patrick Aldermann is killing people, Chief Superintendent Dalziel thinks it's probably all nonsense. But Inspector Pascoe is not so sure . . .