In Portrait of a Suicide, George Valentine, a private investigator, is enjoying a rare day off with his secretary Claire and her brother Sonny. They are on a quest for the perfect picnic spot, but their search leads them to a seemingly abandoned house. While attempting to find a suitable place to eat, they discover a lady's slipper with a note attached, written in lipstick, claiming that a woman is being held prisoner inside the house. This unexpected find piques George's curiosity and sets the stage for an adventure.