A Force of One is a 1979 American martial arts action-thriller film directed by Paul Aaron and starring Chuck Norris, with Jennifer O'Neill, Ron O'Neal, Clu Gulager, and martial artist Bill Wallace in his film debut. Norris plays karate champion Matt Logan, who is hired to assist an anti-narcotics police unit, who are being targeted by a killer. The screenplay by Ernest Tidyman was based on a story co-written by martial artist Pat E. Johnson.

Plot

While investigating a suspected drug den inside a sporting goods store, two plainclothes police officers are killed by a masked assailant using martial arts techniques. In response, Officer Mandy Rust and Lieutenant Sam Dunne approach full-contact karate champion Matt Logan to train their unit in unarmed combat techniques. Logan has a personal stake in the matter, his adopted son Charlie is the son of an addict who died of an overdose.