During a police conference in Geneva, Alec Cling, a detective assigned to the personal safety of Sir Ensor Cobb, British Minister of Security, is murdered and his body found in a car parked in a rose garden.
The car happens to be hired by Superintendent Littlejohn, of Scotland Yard. Cling was a lone wolf when off duty. Saturnine and silent, he seemed to hate everyone and everything, except children, old people and dogs. It was obvious that the case was international at its roots, extending from Switzerland back to London.
Littlejohn is assigned to the case in London. The trail leads him through a seedy hotel in Geneva to a mental clinic in the mountains and from there, to London Airport, where there is quite a commotion before Littlejohn finally clears up the investigation.