Two Marines are sent to South Sea island where they fight over a local island girl.

Young boxer Jack Ranney agrees to challenge 'Young Kilroy' and knocks him out with his first punch. When he is told that Kilroy is dead, Jack hurriedly heads West and finds a job on a ranch, boasting to all the fellows that he is a killer; unimpressed, they call him a greenhorn. Meanwhile, Jack's sweetheart Mary learns that Kilroy is alive, and she heads West to tell Jack the news, arriving just in time to see him single-handedly save the ranch from a raid by the notorious Lopez Cabrillo and his entire gang.