The murder of a young girl proves to be a particularly difficult case for Maigret. While visiting the crime scene, the inspector meets the respected surgeon Professor Gouin, who was involved with the victim. Is the professionally successful, but privately selfish and unscrupulous doctor involved in the crime? Soon the Parisian detective encounters other suspects: a bar pianist who wanted to marry the girl, Madame Gouin and her sister, who bitterly hates her brother-in-law, as well as Dr. Lucile Decaux, the surgeon's assistant ... Based on the 43rd novel in the Maigret series: 'Maigret se trompe' (1953). In the German-speaking world, the novel was published as 'Hier irrt Maigret'.