The winter of 1944. The Nazi juggernaut is in full retreat from Russia. Sergeant Gunnar Jemand is determined to get his men back to Germany rather than die uselessly for Hitler. On the other side of war, Lieutenant Anton Profimov leads the pursuing platoon of Red soldiers.

The Germans reach an SS army camp built over an old Roman fort. Relief turns to dismay: the camp is abandoned; signs of ferocious battle mar the inside of the camp, armor and gear from SS units litter the grounds.

The German search the camp for supplies before continuing their retreat. Jemand works on the camp's damaged radio. Medical specimens of an unsettling nature are discovered along with an overabundant supply of "pork" in a cold storage room. A woman in a chain-mail suit is also found... with a bullet-hole in her head, but still alive.

Jemand fixes the radio but gets bad news: he tells the men they're to hold the camp until reinforcements arrive. When pressed, Jemand informs them, "this is an S.S. Einsatz camp," where "undesirables" were eliminated. Since the war is lost, all evidence is to be wiped clean.

Night falls. The Russians wait for reinforcements before they can strike the camp—gunfire erupts within the camp. Are Ukrainian partisans attacking the invaders? The Russians hold their positions.

At sunrise, the Germans scramble out the fort, bloodied and fewer than before. Among them is a young German nurse, Masha. Before they can flee, the Russians surprise them at gunpoint. A storm front is moving in. The Russians decide to weather it out in the camp despite the protestations of their German prisoners. "What is it you are so afraid of?" the Russians ask..

"Monsters."