On Christmas Eve in a remote Montana town, a long-forgotten warning siren tears through the snowbound darkness.

For decades, Grimlock Island has been off-limits, its old bridge fenced off and marked with signs that winter storms finally rip away. When an unsuspecting couple camps along the island’s quiet shoreline, they cross a boundary that should never have been touched.

Their presence encroaches on sacred territory, and the Sasquatch that have guarded the island for decades surge toward the mainland with brutal force.

What follows is chaos.

Homes are attacked. Families are dragged into the night. People are jolted from sleep and forced to fight for their lives as the monstrous horde tears through the snow-covered streets. With only one sheriff, a single deputy, and a handful of terrified locals to stand against the onslaught, the town must pull together however they can if they hope to see dawn. Among them are a haunted sheriff pushing past old scars, a grizzled veteran with a weaponized truck, and a scattering of survivors who refuse to die quietly.

This Christmas, they aren’t hoping for peace or presents.

They are praying to stay alive.