When his dysfunctional family clashes over the holidays, young Max is disillusioned and turns his back on Christmas. Little does he know, this lack of festive spirit has unleashed the wrath of Krampus: a demonic force of ancient evil intent on punishing non-believers.

After receiving an exotic small animal as a Christmas gift, a young man inadvertently breaks three important rules concerning his new pet, which unleashes a horde of malevolently mischievous creatures on a small town.