San Francisco Police Inspector "Dirty" Harry Callahan (Clint Eastwood) and his new partner, Earlington "Early" Smith (Felton Perry) have been temporarily reassigned from Homicide to Stakeout Duty. Meanwhile, those of the city's criminals who manage to avoid punishment by the courts are nevertheless being killed by unknown assassins. Callahan begins to investigate the murders despite orders from his superior officer, Lieutenant Neil Briggs (Hal Holbrook). A man has to know his limitations.