In a world where giant monsters and humans collide, the monsters are superstar athletes and compete in a popular professional wrestling global sport called Monster Wrestling. A young girl named Winnie seeks to follow in her father's footsteps as a manager by coaching a lovable underdog yet-inexperienced monster named Steve. Winnie plans to turn Steve into a champion so that he can go up against the reigning champion Tentacular.

In a small town in central Oregon, Frank Weaver runs a meth lab out of an abandoned mine. While his young son Aiden waits outside the mine in his truck, Frank and an accomplice are attacked by an unseen creature. Investigating strange noises, Aiden is also attacked by the creature. Frank and Aiden survive their encounter with the creature and return home, where their condition quickly worsens. Frank sets up a locked room and demands that no matter what, Aiden's older brother Lucas keeps them locked inside.