Life on the Hartzenberg family farm in Windchill Town is simple, peaceful, and predictable—until one ordinary Sunday turns into a fight for survival.

When Ralph's loyal dog, Rumble, falls into a deep and mysterious hole in the middle of the field, the Hartzenberg family believes it will be a simple rescue. But what lies beneath their farm is far more terrifying than they could ever imagine.

Hidden deep underground is a dark labyrinth of tunnels, giant nests, and monstrous creatures—mutated mole-rats unlike anything the world has ever seen.

As Ralph ventures below to save his best friend, he awakens a nightmare buried beneath the earth.

Soon, the farm becomes the center of a deadly attack as the creatures rise from below, led by a fierce mother mole-rat and an even more terrifying force—the massive and unstoppable King Mole-Rat.