The body of a young woman, a widow, is found shot to death in a rented house. All the signs of suicide are present: a locked door, a pistol in the deceased's hand... However, the doctor who examined the body at the scene strongly doubts this. After all, the pistol is clutched in the right hand, and the wound is on the left side of the head. The doctor reports his suspicions to Inspector Japp, who, in turn, turns to his old friend, the famous detective Hercule Poirot. Japp knows: the brilliant Belgian delights in this kind of mystery. Poirot also doesn't believe the suicide theory, especially when he discovers that the fingerprints on the gun had been carefully erased, and a large sum of money was missing from the house. But who then killed her? And Poirot begins to draw up a circle of suspects...