It's near Christmastime, 1944, in a German POW camp near the Danube River. The camp is full of Russians, Poles, Czechs... and 630 American sergeants. Based on a stage play and directed by Billy Wilder (The Apartment, The Lost Weekend), Stalag 17 (stalag is German for prison) confines itself to the goings-on with a group of those enlisted men, the prisoners in Barracks 4. They've dug an escape tunnel under their barracks, and hidden the entrance with the pot-bellied stove they're allotted for heat. But when a dash for freedom two of the Americans undertake goes badly wrong, the denizens of Barracks 4 start to suspect they've a rat in their midst, and they think they know who it is.

Sefton (William Holden: The Bridge on the River Kwai) is the camp's entrepreneur. He has amassed a fortune in cigarettes -- the currency common to any penal situation -- from his distillery, which brews schnapps made from potato skins and string, and his rat-racing venture, and lots of other mini-businesses. He trades with the Germans for such gifts as a POW camp can offer: eggs, visits to the compound housing Russian women. But is he swapping more than cigarettes in exchange?

Sefton is a hardass and a cynic -- he takes bets on the tunnel escapees' chances of success, betting against them himself, of course -- but is that what it takes to keep from going crazy in stir? Poor Joey (Robinson Stone) is already gone -- shellshocked, he never says a word, just stares into space and occasionally plays a mournful piccolo. "Animal" (Robert Strauss) is half gone, his obsession for Betty Grable just about having reached the insane point -- when he crosses that line, it's as sad as it is funny. The others -- including a POW played by a very young Peter Graves -- seem to endure by tweaking the Germans, engaging in a seeming friendly camaraderie with a guard, Schulz (Sig Ruman), that only just masks their open hostility.

But it's Sefton's treating with the enemy that inspires the most animosity among his barracksmates, and the situation threatens to boil over when a new prisoner -- Lieutenant Dunbar (Don Taylor), who's awaiting transfer to an officer's camp -- is accused of espionage, and a plot is hatched to save him. Will the rat be found out before he can give away the plan?

The humor is of the gallows variety. The characters are men worn down to nubs, intent on staying alive and ready to turn on any who willingly weaken the group... while still retaining the compassion to support one like Joey. The central question the film asks -- Is it every man for himself, or strength in numbers? -- is left unresolved, ultimately. And yet Stalag 17 leaves you feeling somehow good about life, as if the ways of survival aren't quite as important as recognizing that the instinct to survive can itself endure quite a lot of abuse without being killed.

And that thought is comforting, if only in a bitter way.