When the body of Mimi Clark, wife of an American industrialist, is found in the basement of the luxury hotel Majestic on the Champs-Élysées, suspicion quickly falls on one of the staff members. However, Inspector Maigret has doubts and begins an investigation in the hotel's catacombs that wears down the personnel. Then a lead takes him into Mimi's past, when she was a hostess in a nightclub in Cannes. Suddenly, a second body is found in the hotel basement.