Jules Maigret, Chief Superintendent of the Parisian police, is bourgeois, cosmopolitan, softhearted, a pipe smoker, and happily married both to his job and his wife. Maigret’s underlings nickname the elderly woman who keeps calling “the Madwoman.” Yet in fact she is a respectable widow, who complains to the police that an intruder is shifting things about in her tidy apartment. Some of the police dismiss her as paranoid, but she claims it is a matter of life and death. Out of kindness, Chief Superintendent Maigret agrees to follow up on her story. Before he can, however, the woman is murdered. Maigret sets out to find out why and by whom.