In the forests of Siberia, a Soviet soldier, Lieutenant Zakharov, is monitoring a village in the distance that has had a disturbance, he beckons his men to approach. As the soldiers enter the cabins, they see the remains of the massacred villagers. After calling in their horses and gathering any useful supplies, their scout Okhchen determines the way the monsters went after attacking the village.
Presuming they were returning to their barrow, the soldiers pursue the monsters. After firing a green flare into the air, Zakharov's friend and subordinate, Sergei, questions why the teams are spread so far apart. The lieutenant reveals he also asked that but that the Major wanted to cover more ground and thought each team could handle on its own. When Sergei asks about air support, he replies that their air force is committed to the defense of Stalingrad.
At night, Okchen takes the first shot at one of the monsters and eventually a firefight starts. The monsters circle the team and kill several soldiers but the team comes out victorious. As day rises and soldiers tend to wounded and burn the bodies, Okchen discovers a frozen body near the cliff face. It belonged to a Soviet Cheka officer who died some time ago. Zakharov takes the dead officer's journal and the team takes shelter for the night in a crashed warplane.
Zakharov and Okchen see in the valley below that another team is engaging the monsters and losing but decide they can't help them. Inside the plane, Zakharov and Sergei discuss the journal they discovered. The Cheka officer, Major Grishin was an occultist sent by the Soviets to conduct black magic with the Koryaks. They sacrificed a woman to summon the monsters. However, the beasts could not be controlled, slaughtering the black magic practicioners and Grishin. Sergei thinks they should return from the field with this information, believing the journal has the key to ending the plague of monsters. However, Zakharov explains that the Soviet Union will more likely kill them in order to keep their mistake hidden, and instructs them to press on.
The soldiers discover a massive ghoul barrow in the side of a mountain, larger than any they have seen. Pogodin and Okchen are sent in to set charges to seal the barrow and kill the monsters. The charges go off successfully but causes a landslide over the entire area, killing the two soldiers and revealing that the barrow was even bigger than they had thought.
The soldiers realize their horses can't outrun the horde and decide to make a stand. The youngest, Malenchenko, asks the lieutenant what task he should take as Sergei brings the fastest horse per the lieutenants' request, offering the mount to Malenchenko. The lieutenant explains the young soldier that one rider may be able to get through if the rest remain to keep the delay the creatures. Malenchenko resists, insisting that he fight and die with his comrades. Lt. Zakharov ignores the request and instructs the young man to give the Major their current co-ordinates, with instructions to bomb the area into scorched rubble. Malenchenko reveals that Lt. Zakharov his his father, and pleads one last time to remain and fight. The lieutenant orders his son to go before turning and walking away, as Sergei tells Malenchenko to "ride like hell and don't look back," before spurring the horse into a gallop.
The horde attacks in force. Despite fighting viciously, the Soviet soldiers are overrun. Lieutenant Zakharov is the last standing as he sets off the charges they placed on the mountain to buy time for his son to escape. Some time later the monsters, clear in their victory as they fight amongst themselves for the mutilated remains of the soldiers, turn their attention skyward to a large formation of Soviet bombers, a balalaika playing as the area is obliterated with ordnance.