Louise Filon is found shot in her apartment. She'd been known as Lulu when she'd been on the streets, but was now apparently being kept by someone. The cleaning woman, Désirée Brault, whom Maigret recognized from her many brushes with the law, said as little as possible. So did the concierge. Eventually Maigret learns of Lulu's boyfriend, a musician, Pierre Eyraud. He's gone into hiding, apparently on reading the news. Lulu had had a serious brain illness, but had gotten surgery and recovered, after which she'd moved to the Rue La Fayette, and then to her present apartment on the Avenue Carnot. The tenant above her, Étienne Gouin, is a famous brain surgeon, 62.
Maigret learns that Lulu had been pregnant, and through one of Pierrot's friends, convinces Pierrot to come in to talk. He lets him go, apparently innocent. Maigret interviews Gouin's wife, Germaine Gouin and sister-in-law, Antoinette Ollivier, and finally his assistant, Lucile Decaux. After that Gouin calls Maigret and asks why he doesn't interview him directly, so Maigret goes to his house with Lucas. Gouin says he's received a call from Désirée Brault, who claims to have found the gun and hidden it from the police. Maigret sends Lucas for it, while he remains with Gouin, whose testimony eventually makes it clear that it was his wife who killed Louise, apparently out of jealousy. Her sister, Antoinette, who was with her at the time and hated Gouin, waited outside the door.
This report prepared by Dana Samson