British airmen embark on a daring mission to destroy a heavily fortified German rocket-fuel plant in Norway, and to ensure success the RAF pilots have to bomb an overhanging cliff to collapse it onto the building. The plan threatens to unravel, however, when a Norwegian freedom fighter plotting a land attack to coincide with the air strike is captured by the Nazis. Second World War drama, starring Cliff Robertson, George Chakiris, Donald Houston and Harry Andrews