When a madman dubbed 'Scorpio' terrorizes San Francisco, hard-nosed cop, Harry Callahan – famous for his take-no-prisoners approach to law enforcement – is tasked with hunting down the psychopath.

While the Civil War rages on between the Union and the Confederacy, three men – a quiet loner, a ruthless hitman, and a Mexican bandit – comb the American Southwest in search of a strongbox containing $200,000 in stolen gold.