An elite group of mercenaries, each with highly specialized skills, are hired to take out a German command center deep within a limestone cavern system.

During World War II, five military misfit men are recruited for a suicide mission behind enemy lines to locate and destroy a German headquarters located in a remote region of Yugoslavia. They make up of the team leader known only by his code-name 'Mister'; an eccentric pilot called 'Flyer'; a German doctor called Dr. Herz; a nihilist gung-ho named Fierro, and an army chaplain with a knowledge of explosives called 'The Reverend'. They meet up with a female resistance fighter, named Mirka, who assists them in their travels through enemy territory in taking down many German targets including an airfield, a supply depot, and a village. With German aircraft hindering their movements, they must find a way into the German field headquarters, located in a remote limestone cave, destroy it and somehow return home alive.