A wealthy Englishman emotionlessly identifies a picture of his dead wife.

Maigret, accompanied by an inspector from Scotland Yard, visits a small island where a man, who carried an old letter coming from Maigret, was murdered.

A shot is heard at 3pm from the waiting room of a shady financier. Minutes later he is found shot dead. Among the witnesses are two inspectors waiting to issue a summons. A suicide? Maigret sees it as a classic Agathe Christie mystery: enclosed scene and limited suspects, all of whom have motive. He keeps everyone there and lets them simmer until someone comes to a boil.