The first World War rages on when a group of American soldiers find a mysterious artifact that can summon the ancient evil of the Krampus. After the men are killed in action, the artifact is sent to the commanding officer's widow who is a teacher at a small-town orphanage. The orphans accidentally summon the Krampus and the teacher, and her pupils are forced to battle this ancient evil.
The Krampus is a horned anthropomorphic figure who, in the Central and Eastern Alpine folkloric tradition, is said to accompany Saint Nicholas on visits to children during the night of 5 December, immediately before the Feast of St. Nicholas on 6 December. In this tradition, Saint Nicholas rewards well-behaved children with small gifts, while Krampus punishes badly behaved ones with birch rods.