X + YY: Formel des Bösen: Playboy Red Mitchell suffers from chromosome malformation X+YY, a dangerous deformity of the libido. At night, driven by inner turmoil, he roams the streets of the city and murders women. Preferably young, pretty girls who become his victims after he has seen them naked in his imagination with his X-ray vision and then undresses them in real life to kill them. But he soon leaves traces behind, and a cunning detective who suspects his chromosomal drive is on Mitchell's trail...