Description
Willard Stiles is a meek social misfit who develops an affinity for rats. He lives in a large house with his cranky and decrepit mother Henrietta. On his 27th birthday, he comes home to a surprise birthday party thrown by his mother, where all of the attendees are her friends. After leaving the party in embarrassment, he notices a rat in his backyard and tosses it pieces of his birthday cake.
His mother tells him to eliminate the rats. Willard uses food and a plank bridge to lure them into a pit in the backyard, then begins filling the pit with water to drown them. However, moved by the rats' piteous squeals as they realize their plight, he replaces the plank, allowing them to get to safety. He later begins playing with a rat he names Queenie. A white rat, which Willard names Socrates, becomes his best companion. Other rats emerge, including a bigger black specimen whom he names Ben.
At work, Willard is tasked with an overwhelming number of accounts by his boss Al Martin, who usurped the business from Willard's father. Willard asks Al for a raise, having not received one since his father's death despite working after hours and weekends. Al refuses and pressures Willard to sell him his house. Willard sneaks into a party that Al is hosting, opens a rat-filled suitcase, and urges them to get the food. The guests are terrorized by the rats, and Al destroys the catering tables trying to fend them off. The next day Willard's mother dies. He is informed that she had no money and the house is heavily mortgaged.
Willard starts bringing Socrates and Ben to the office on Saturdays to keep him company while he is the only one there. His friend and temporary assistant, Joan, gives him a cat named Chloe to comfort him. He hands Chloe off to a stranger. Meanwhile, the rat colony is growing and Willard cannot afford to keep feeding them. After overhearing one of Al's friends boasting of a large cash withdrawal, he sneaks into the man's house and orders his rats to tear up the bedroom door. The man and his wife flee the house upon seeing the rats, and Willard steals the cash.
The next day, a worker spots the rats. Al bludgeons Socrates to death, devastating Willard. When Joan refuses to persuade Willard to sell his house to Al, he fires her and Willard, believing that unemployment will force Willard to sell. That night, while Al is at work, Willard enters the office with his rats. He confronts Al over the death of Socrates, the mistreatment of his father and Al's machinations to buy his house. As Al attempts to attack him, Willard instructs the rats to kill him. As he is being eaten alive, Al falls out a window. Unnerved by Al's gruesome death, Willard abandons the rats at the scene. The next day he places his remaining rats into crates and drowns them in the backyard pit. He then seals up any holes through which the rats could enter his house.
Willard has dinner with Joan at his house, telling her of his newfound self-confidence, which he attributes to her and Socrates. Over the course of their conversation, however, he sees Ben staring at him from a shelf. Investigating, he finds hordes of rats in the basement. He orders Joan to leave and locks the door behind her. Willard offers Ben and the rats food, which he mixes with pesticide. Ben sniffs the pesticide box and squeals loudly, alerting the others. Willard chases Ben upstairs, cornering him in a storage room. He barricades the door against the other rats, leaving Ben to face him alone. While Ben eludes Willard's attacks, the rats gnaw through the door. As the rats attack him, Willard shouts, "Ben, I was good to you!"
