I remember that David Warner is a mild-mannered young British officer guarding a naval gun station in the North Atlantic, in peacetime after World War Two. It's a cold, remote, unpleasant duty, and he's desperate to transfer out of there. But the transfer must happen soon, before he's more than halfway through his service time - otherwise, the War Department won't bother retraining him for a new post, and he'll be stuck. He's got a fiance or something he needs to get back to, but he also reports to an unsympathetic superior who doesn't like him and will do anything to delay his paperwork - effectively denying the transfer. So we have a sensitive, educated young upperclassman, the opposite of any kind of warrior, fighting not the enemy but "the system:" in this case, the British military bureaucracy.
He only needs to get through one more night of guard duty without mishap, which should be easy because there is absolutely nothing going on. But he has trouble relating to the men under his command, especially Nicol Williamson, a borderline psychotic from the slums who constantly tests Warner's authority and creates havoc wherever he goes. So now we've got class warfare in a power struggle between the civilized and the savage. Williamson is brilliant as he deserts his post, gets drunk with his buddy Ian Holm (also excellent), vandalizes the base, and just gets crazier and more dangerous as the night unfolds.
Warner has to control this lunatic and somehow correct and conceal the escalating troubles before his superior finds out. There's a lot of suspense as Warner becomes increasingly stressed, racing the clock between inspection rounds. As another reviewer points out, there is also a lot of talk, in the somewhat-Freudian, somewhat-socially conscious theatrical style of the time. But the conflict and rising tension is splendidly executed, like a first-rate stage play brought to the screen, and Williamson's bravura performance is one of the best in his outstanding career. This is a little-known movie that I recommend.
Best line, Williamson, sweating drunk in a moment of insane clarity: "I should not be at large...!"
