Inspector Maigret shadowed by Mr. Pyke of Scotland Yard travels to Porquerolles, a small island off the southern coast of France, where a murdered man is found to have a letter from Maigret in his possession.  The Inspector spends a few days on the island observing the seedy cast of characters and then arrests two men for the murder.  They had been involved in a swindle forging works of art and selling them to a rich, old English woman and when Marcellin discovered their ploy and wanted in, he was killed.  Another brilliant solution provided by Jules Maigret.