In the midst of a snowstorm, young widow Meg Lassiter is trying to get home. At the Lassiter farmhouse uninvited mutant rats are waiting. These rats are not just seeking shelter, warmth, and food. They're seeking the annihilation of any human who crosses their path. Meg must find the strength and courage to face the genetically enhanced rats. Trapped in her snowbound home, armed with only a shotgun and the desire to survive, Meg wages a one-woman war against creatures scientifically engineered to outwit, outrun, and outfight the human race.