Following an American general’s aircraft being shot down over Nazi Germany, the responsibility of rescuing him falls to “Smith” (Richard Burton), who must guide a specialized unit deep into German territory. Their objective: extract the general before he divulges sensitive details about impending Allied operations under the influence of scopalamine. Almost immediately upon arrival, complications arise; one team member doesn't survive the initial parachute descent into a snow-covered woodland, forcing “Smith” to depend increasingly on American Ranger "Schaffer" (Clint Eastwood). These men are strangers to each other, and Schaffer seems genuinely confused about his participation in what is clearly a British undertaking. The general is being detained within the “Schloß Adler,” a fortress perched high on a rocky promontory reachable only by helicopter or cable car—and surrounded by numerous troops. It doesn’t take long for suspicion to surface regarding a possible traitor among them, escalating the danger as they struggle against the harsh conditions, evade pursuing enemy forces, and attempt to penetrate the castle itself, where even more dangerous trials await their shrinking group. Alistair MacLean consistently demonstrated an aptitude for translating his novels into film in a manner that informs the audience of certain details before the characters do, and this approach proves effective here, producing a fast-paced adventure anchored by Burton’s charisma and Eastwood’s understated presence. The narrative is enriched by a solid supporting ensemble, including Derren Nesbitt as the sinister SS “Von Hapen” and Mary Ure in the role of the capable "Mary." The film moves swiftly over its 2½-hour runtime, offering plenty of exciting action sequences and an ending that maintains suspense until the very end.

Source on TMDB