This high-impact thriller finds exiled crime boss Colini (Marc Lawrence) training young Sicilian thug Giordano (Henry Silva) to be a heartless assassin. Giordano, dubbed Johnny Cool, goes to America with instructions to wipe out the mobsters responsible for Colini's deportation. Johnny travels the country on a murderous rampage and finds love with a troubled singer (Elizabeth Montgomery), whom the mob abuses in an effort to stop the cold killer.