Who'll Stop the Rain? (1978)

A jaded journalist, John (Michael Moriarty), and a Vietnam vet, Ray (Nick Nolte), are adrift after returning home from the war. With not much to lose, they hatch a scheme to smuggle heroin from Vietnam into the U.S., which stands to make them a fortune. Instead, the pair and John's wife (Tuesday Weld) find themselves on the run from drug dealers and a crooked DEA agent (Anthony Zerbe). Along the way, Ray shows their opponents some of the useful combat skills he picked up in the war.