Set during World War II, an allied aircraft is shot down over Nazi controlled territory. The Nazi's capture and imprison American General George Carnaby (Robert Beatty) who is the lone survivor. The British assemble a team, mainly of British commandos to either kill or rescue the general who has complete knowledge of the Allied D-Day invasion plans, before he is made to reveal the plans to the Germans. The rescue team includes Major John Smith (Richard Burton), American Ranger Lieutenant Morris Schaffer (Clint Eastwood) and a female agent, Mary Elison (Mary Ure). However, as the mission progresses all is not as it initially seems...