Seeking a carefree weekend away from the stresses of college life, three sorority sisters—Mary, Zoe, and Jenn—arrive at a secluded lakeside cabin belonging to Mary’s aunt. Jenn is dealing with lingering trauma from discovering her boyfriend, Sam, has been cheating on her. Her friends hope the rustic getaway, free from cell service and
distractions, will lift her spirits. Shortly after their arrival, Jenn’s repentant boyfriend Sam, along with his friends Tommy and Buck, track them down to apologize and win Jenn back. While tensions initially flare between the groups, the boys are eventually invited to stay, setting the stage for romantic reconciliations and petty rivalries.Unbeknownst to the group, the idyllic lake hides a deadly biohazard. A truck transporting barrels of toxic chemical waste strikes a deer on a nearby road, causing one of the barrels to roll down an embankment and plunge into the water. The toxic sludge contaminates the local ecosystem, specifically affecting a dam constructed by a colony of beavers. The mutated creatures are transformed into rabid, flesh-eating monsters driven by a terrifying hive-mind bloodlust.The horror shatters the peace the next morning when Buck goes fishing and is brutally attacked and dragged into the water by the zombeavers. When he fails to return, Tommy and Sam search the shoreline, discovering his
severed hand. Panic sets in as the mutated rodents launch a coordinated siege on the cabin, chewing through the wooden walls and trapping the terrified college students inside.As casualties mount and the beavers breach the barricades, the friends are forced to fight for their survival using whatever makeshift weapons they can find. Trust fractures as infections spread among the group; Jenn is bitten and slowly begins to transform, her demeanor shifting as the zombie virus takes hold of her mind and body. In a desperate bid to escape, the remaining survivors attempt to flee on a raft, but the water proves to be their deadliest trap. The zombeavers swarm the lake, destroying the raft and picking off the characters one by one in a series of gruesome, frantic encounters. In the grim finale, the survivors are completely decimated by the relentless, chewing horde, proving that nature always bites back.