On the island of Porquerolles, not far from the south coast of France, the murder of Marcel Pako was discovered. Locals knew him by the nickname Marcelin. He lived on a boat, had no permanent job, and recently boasted about knowing Commissaire Maigret.
Now it is Maigret who must investigate the case—under the watch of Mr. Pyke, a representative of Scotland Yard, who has come to study his famous methods.