An oddball animal biologist local field researcher named Marshall Clarke Simon Bossell is investigating the disappearance of local wildlife and stumbles upon an unidentified slimy residue that hints at a threat hiding in Langdon’s woods. At the same time, Amy Harding [Pamela Gidley] moves into her old cabin in the forest, bringing along her cat Frankie [Merlin], a stash of money, and a lifetime of belongings. As she works to make the cabin habitable, she encounters a moist substance that spoils a piece of cake and fears she might be dealing with mice. Outside, she runs into Mr. Peterson [Norman Forsey], who is searching for his dog Florence, murdered by an unseen creature, and he bluntly tells her to get out of Langdon.
Inside the general store, Mrs. Miller [Helen Moulder] is helpful but out of supplies; she offers insect repellent in place of mouse traps and sends Amy back with limited options. Back at the cabin, Amy finds Frankie’s bowl empty and feeds the cat canned food. When she takes a bath, the lights fail and she heads to the shed to check the generator. In the shed, slimy residue drips into her hair. She later returns to the store, where Mrs. Miller lends a poison sprayer and Amy meets Marshall Clarke, who offers help after her car breaks down. As they head back to the cabin, something bites Amy’s hand, and the couple discovers Frankie’s lifeless body in the bathroom, a grim clue to what is stalking Langdon. They manage to kill one of the lizard-like creatures, which Marshall identifies as a mutant gecko capable of spitting blinding venom to paralyze prey. The storm worsens, forcing them to attempt an escape, but a snowstorm and a crash cut their attempt short.
Seeking shelter, they approach Mr. Peterson’s cabin only to find it already overrun by the same creatures, which devour Peterson. Amy blows up the cabin and, in a dramatic escalation, takes out the accompanying truck. With nowhere else to turn, they retreat to Amy’s cabin as the blizzard rages. Inside, Marshall is attacked and blinded by the poisonous venom, while Amy fights to survive. In a desperate bid, she sacrifices her goldfish by drowning a lizard, only to learn the creatures are amphibious, forcing her to electrocute one by hurling a lamp into the fish tank. She then destroys the remaining eggs that lie in the attic.
The next morning, Marshall’s sight returns just as someone taps on the outside. Uri Romanov [Valery Nikolaev] arrives and knocks Marshall unconscious, revealing Amy’s true past: her real name is Alex, and Uri believes the money belongs to him. Uri pursues Amy’s stash, and she tries to lure him into a trap by claiming the money is in the closet, but his gunfire continues anyway. Uri is driven toward the attic where more eggs hatch and lizards swarm, and Amy finally forces Uri into a confrontation that ends with him falling into the fireplace as more eggs hatch and lizards swarm. Amy shoots Uri repeatedly, and she and Marshall set the cabin aflame, escaping in Uri’s car only to find it breaking down. Marshall investigates the hood and discovers eggs hatching inside the engine, while lizards emerge from the car’s interior to attack. Marshall urges Amy to unlock the door as she panics, then seizes a cigar from the passenger seat and throws it into the gas tank, blowing up the car and killing the surrounding lizards.
Carrying an unconscious Amy to the nearby general store, Marshall enlists Mrs. Miller’s help to remove a lizard that has eaten into Amy’s leg. The extraction is painful, and as Marshall searches for a flare gun, the lizard feeds on Mrs. Miller’s life. Amy reappears, grabs the flare gun, and blasts the lizard in the mouth, sending it flying into the wall where it explodes. The danger recedes just long enough for the two to collapse on the floor and share a quiet, exhausted kiss.
