Baretta has to go on the run to clear his name after he's framed for the murder of a gun dealer he was investigating, who was selling weapons to teenagers.
Even though he has no evidence Barreta suspects a man named Mazurski of killing a petty criminal. His hunch is based on the man's wife Doris being injured during a burglary committed by the now dead man.
With the help of a nun and a deaf mute nicknamed Shoes, Baretta tries to find a serial rapist who initially poses to his female victims as a plainclothes detective.
Baretta comes to suspect that his close friend, a music store owner, may not only be a drug dealer but may be unknowingly selling heroin so pure that it's killing his customers.