Desperate for companionship, the repressed Willard befriends a group of rodents which inhabit his late father's mansion that is deteriorating. In these animals that are furry, Willard finds temporary refuge from abuse at the hands of the bedridden mother and his father's old partner, Frank. Soon it becomes clear that the brood of rodents is willing and ready to exact a vicious, deadly revenge on anybody who dared to bully their fresh master that is sensitive.