A serial killer is on the loose, murdering certain women around the city. While travelling on a train on his honeymoon, Mario (Antonio Sabato) sees his wife brutally attacked aboard the train and after the killer gets away, the police accuse Mario of attacking his newlywed wife. Police decides to hide the fact that Giulia (Uschi Glas), Mario's wife is alive in order to protect her from the killer. Mario sets out to prove his innocence by attempting to solve the "Puzzle of the Silver Half Moons", which leads him to the hotel where he met his wife, a man name Frank Saunders, Christian Church's tour, a group of hippies and Frank's ex-mistress. The film contains some very violent murders, some shown from the point of view of the knife-wielding, black-gloved killer, as he stabs a woman in her bed, bashes in the head of a prostitute, strangles a female artist with a telephone cord, drowns a mental patient in her bathtub and even uses a power drill on one unfortunate victim. Mario must catch the real killer in order to prove his own innocence.