Richard Burton and Clint Eastwood star in this Second World War action adventure based on Alistair MacLean's novel. During the war, seven Allied agents are selected to rescue an American general from the impenetrable German fortress Schloss Adler. In charge of the team is British Major Smith (Burton), with American Lieutenant Schaffer (Eastwood) as second in command. Parachuting into the enemy territory in German uniforms, the squad discover one of their number dead on arrival, and Smith suspects that he may have a traitor amongst his unit.