The sexual relationship between a successful woman and her brother, an introvert, hypochondriacal youth, who is also a pornophile.
Passionate rock'n roll dancer, Rodolfo has his partner Ornella as a partner. Frozen by the frivolous behavior of the boy, however, the young girl no longer wants to learn to dance with him. Finally, when Rodolfo had lost all hope of replacing it, Ornella, who has meanwhile accepted the court of a ballroom impresario, returns to her decision.
A pharmacist is murdered, and a woman happens to see the culprit leave the scene. She soon finds herself being stalked by the killer.