Francis Pettigrew, a former barrister and sometimes amateur detective, is plucked out of what promises to be a peaceful retirement in the Home Counties to deputise for the County Court judge. The proceedings offer him some unexpected insights into the lives of the new neighbours that he has—until now—only observed through his field glasses.

When the body of a penniless widow known for her good works is found on Yew Hill, a famous local beauty spot, Pettigrew is drawn into the case as a witness. Despite his best efforts to leave the inquiry to the police, it is he, with the unconscious help of a teenage boy, who puts the finishing touches on the solution.