Nobody at the headquarters of the Judicial Police gives credence to the testimony of Arlette, a dancer in a strip-studio in Pigalle who comes to the police station at four-thirty in the morning, drunk, assuring that she has heard someone Oscar confess his intention to murder a Countess. The case only reaches the ears of Maigret when, shortly after the unexpected appearance of Arlette at the police station, his body is found dead and, hours later, that of a Countess: both have been strangled in their homes. Installed in the Picratt's hostess club where the dancer worked, Maigret observes and interrogates the nocturnal characters who populate the underworld of Paris to reconstruct the bond that united the two women strangled with the mysterious Oscar, and thus discover the murderer. A new vibrant plot in which Maigret brings to light the most dismal human passions.