Isotta is the wife of a mafia boss living in Hollywood named Sam Mordoso. After learning that a certain film director, Mark Shannon, is making a movie about one of the most notorious crime bosses in the underworld, Sam and Isotta arrange to have him gunned down. He survives, but fearless rogue gangster and heroine of the series, Cat Morley, decides to investigate this attack, as she is a friend of Shannon's. Her search leads her to Mordorso's residence. Posing as a housekeeper looking for work, she is invited inside, but is quickly gassed and taken down below. Isotta then restrains Cat and subjects her to a sadistic flogging machine while also torturing her with a nail gun.
Up above, Isotta makes love to her husband, while also discussing what should be done with the intruder. Sam suggests that they killer her, and his wife wholeheartedly agrees. However, upon returning to the basement, she discovers that Cat has seduced and knocked out the man that was supposed to be guarding her. Gun in hand, Cat leads Isotta upstairs and then shoots and kills Sam. She then forces the Contessa to take her to the front gates and exits the property.
Outraged, Isotta heads to the hospital where Shannon is staying, posing as a patient. When taken to her room, the woman quickly murders one of the nurses by strangling her and then throwing her out of a window. She then locates Shannon's room and shoots the man dead in his hospital bed, before escaping. Isotta decides to lay low in a nearby lesbian cabaret club. Hot on her trail, however, Cat manages to follow her there, and upon seeing the Contessa enter the restrooms, makes her move. The avenging gangster girl then pistol whips her and drowns the now semi-conscious woman in the toilet.