After suffering a concussion from a grenade blast in Vietnam, Sgt. Frank Johnson has been getting flashes of his childhood in which strangely he is a ninja. Because of this, he is given a codename: "Black Fire" by the US Army. He is sent to San Sebastian together with his buddy Sgt. Jim Anderson to work as U.S. military advisers. One night, Sgt. Johnson discovers Capt. Salcedo of the local corrupt army is trying to transport arms.