San Francisco Homicide Investigator and Vietnam veteran Vince Torelli strives to clean up the violence in San Francisco but, after a suspect in a double murder is killed during an attempted arrest, he finds himself also protecting the police officers of the city he considers family. His efforts put him in the line of fire when he's targeted. The brother of the suspect victim wants revenge on the officers responsible and he'll stop at nothing. He kidnaps Vince, a man obsessively loyal to his job as well as those he works alongside, a man as smart and committed to his principles as the criminals he catches almost without fail. Vince knows best, though, a blood debt always demands payment...