Plot
Maigret, the former Detective Chief Inspector of the Paris Judicial Police, is now retired and living in Meung. Early one morning he is awakened by his nephew Philippe Lauer, a junior detective who was inspired by Maigret to join the police. The previous night Philippe had been on a stakeout at the Floria nightclub in Paris, whose owner, Pepito Palestrino, was to be arrested for dealing in cocaine and involvement in the murder of a criminal named Barnabé. After the club had closed for the night, Philippe heard a gunshot inside and found Pepito dead. Panicking, he fired a shot, found the murder weapon and put it near the victim's hand, then bumped into a passer-by as he was leaving the nightclub. He fears he will be arrested for the murder.
Maigret and Philippe take a taxi to the crime scene where Chief Inspector Amadieu, Maigret's successor as divisional head, has already arrived. The passer-by, Joseph Audiat, identifies Philippe as the man he had seen leaving the nightclub. Philippe is suspended from duty.
Maigret goes to the Floria where he talks with Germaine Cageot, a criminal and police informant who he believes is the real owner of the nightclub and was involved in Pepito's death. After Cageot denies everything, Maigret leaves with Fernande, a prostitute who frequents the nightclub.
At Fernande's apartment, Maigret tells her he suspects Cageot and Pepito killed Barnabé. He offers her 2,000 francs to find evidence against Cageot. She goes to the Tabac Fontaine, a café near the Floria, where some associates of Cageot regularly play cards. She leaves with Eugène, one of Cageot's associates.
Philippe is arrested and put in custody. Maigret goes to police headquarters where he learns that Cageot knew about Pepito's imminent arrest. Cageot has also arranged for Fernande's arrest.
Maigret goes to Tabac Fontaine where he sits for 12 hours observing Cageot's associates, including Audiat and Eugène. When Audiat leaves just after 1 am, Maigret follows him. Audiat leads Maigret to a deserted backstreet where Eugène tries to run him over in his car but hits Audiat. Maigret treats the injured Audiat and tries to convince him to give evidence against Cageot.
Maigret convinces the chief of the Judicial Police to bring Cageot and his gang in for questioning. However, they deny knowing one another and are released. Maigret sees Fernande, just released from custody, waiting for Eugène by Eugène's car and realizes she is now Eugène's girlfriend.
Maigret goes to Cageot's apartment, ostensibly to offer him money to exonerate Philippe. As they negotiate, Maigret secretly wedges a small piece of wood under the receiver of Cageot's telephone. He has arranged for a detective and two stenographers to listen to their conversation on the other end of the line. Maigret says he knows Cageot ordered the murders of Barnabé and Pepito and is certain that Audiat will soon inform on him. Cageot says that Audiat is already dead and he has arranged for Eugène to be killed if he talks.
Eugène enters with Fernande, explaining to Cageot, who is now holding a pistol, that he had tried to ring him, but his phone was engaged. They see a police car pull up outside. Maigret fires at Cageot, hitting him in the hand and causing him to drop his pistol. Eugène jumps out the window and flees as two policemen enter the apartment. Fernande says they will never catch Eugène. She is proved correct: a month later she joins him in Istanbul where he runs a nightclub. Cageot is sent to prison. Philippe returns to him home town in Alsace.
