Francis, an intelligent and cynical cat, is moved to a gloomy, dilapidated house with his owner Gustav Löbel, a romance writer and architect. The top floor of the house gives off a mysterious and distinctly chemical odor. During Francis's exploratory tour of the house, he discovers the body of a cat who was killed by a bite to the neck. At the crime scene, he meets and befriends Bluebeard, a foul-mouthed, one-eyed and mutilated Maine Coon.