"Night Traaaain! To Mundo Feeeeeeeenay!"
As far as I can tell, in Red Zone Cuba, a profoundly unappealing convict played by the director escapes from prison, where by the looks of him he was sent for being a psychopath who eats his victims. He runs in to two Samuel Beckett characters, stewing their boots in a blasted hellscape, and together they make their way - via a Coleman Francis motif, the light aircraft - to sign on as mercenaries, which as it turns out means joining up with the Bay of Pigs invasion.
They get shipped out to Cuba, wet their pants, get captured by a cigar-chewing Fidel Castro impersonator in a false beard, escape the least-well secured stockade in the history of cinema, and haul ass for the nearest light aircraft. They also heroically abandon their CO to die, but only after he reveals that he's the owner of a mine full of precious minerals back in the USA.
They show up at the mine and push their CO's wife around until she agrees to help them exploit the fabulous tungsten wealth therein; they also do a little murdering to keep their hands in. It's all in vain though as soon enough the cops show up to shoot them to death, and also their CO turns up, having not died of his wounds in Cuba after all.
Everything is shot in the inimitable Francis style; a director whose eye captures nothing but greyness, dullness, and especially ugliness. Like all his movies, there's not a single frame that doesn't look like a grainy newsprint photograph accompanying an article about someone who turned out to have a chest freezer full of nurses.