In 1898, during the Cuban War of Independence from Spain, a former U.S. Cavalry Captain, dishonorably discharged from the army, is a gun-runner. He, and other soldiers of fortune, renegades and outcasts, tempted by high profits, are defying the Spanish blockade of Cuba and are smuggling guns to the Cuban revolutionaries from Tampa, Florida. The ex-Cavalry Captain, Caleb Cash Adams, and his former Sergeant, Trasker, attempt to deliver a large weapon-shipment to representatives of the Cuban rebels but are told the weapons should be delivered straight to Cuba. Having no other customers for his weapons, Adams agrees but doubles his price. Fighting off a gang of hijackers they arrive in Tampa, where they are told to load the shipment onto an old river-boat, captained by an ex-Confederate Navy man, Capt. Sidewheel Jones. Adams and his men also notice that another gun smuggler and competitor, Clay Pike, is also loading a shipment of weapons on the river-boat. Adams and Pike are old enemies, g