Four women were murdered, each was knifed and, though they had their clothes torn, they weren't molested. As the famed police inspector Jules Maigret pieces the clues together, he comes to realize that for the elusive man that he suspects to be unmasked, he has to set him a trap.

Gangsters from the United States try to kill a key government witness whose testimony could help land an influential mobster in jail. It's up to detective Maigret to deal with the FBI and a series of underworld figures to save the life of the witness...

Police Commissioner Jules Maigret returns to the small village where he spent his childhood at the request of the Countess of Saint-Fiacre, who has received a disturbing anonymous letter.