It follows the meandering adventures of an escaped convict and two ex-convicts he recruits along the way as they become involved in the 1961 Bay of Pigs Invasion, and a quest to find a hidden treasure in a tungsten mine.

Carradine also sings the film's opening theme song, "Night Train to Mundo Fine" (pronounced "Finé"), with musical accompaniment by Ray Gregory and the Melmen.

The three make their way to an airstrip run by Cherokee Jack who flies them to a military training facility, where they will be paid to take part in the Bay of Pigs Invasion.

The trio find an airstrip and steal a light aircraft to return to the U.S. Back on American soil, the three engage in a variety of crimes to get to the home of Chastain's wife to help her mine the metals her husband had mentioned in Cuba.

They throw café owner Cliff Weismeyer down a well and Griffin rapes his blind daughter, then they steal his car and escape; they also hop Mr. Wilson's train in Albuquerque, New Mexico.

The law catches up with them along the way and police cars approach them; Griffin impulsively shoots Ruby and runs into the fields, while Landis and Cook are arrested.