Maigret is called to the high-class Hotel Majestic to investigate a body. The wife of a wealthy American has been killed - but to Maigret's surprise she has a gun in her purse. He begins to follow up the handful of clues that could explain her secret life and her demise.

François Cardinaud is one of the richest shipowners in the region. But this success arouses resentment and jealousy. When Marthe, his wife, leaves the home without warning, Cardinaud sees her life cracking little by little.