Stan, Francine, Hayley and Steve are shopping at the Langley Falls Shopping Mall. Hayley is disgusted that the mall has ruined the land of indigenous people, meanwhile Stan is spending his $20,000 bonus on things he doesn't need. Francine sees a kiosk available for rent and she wants to fulfill her dream of managing one. Francine gives Steve a bag of muffins to take to the movies, Steve says his friends would pay to have her muffins. Hayley takes a walk outside and sees that mall expansion is destroying more land.
Steve and his friends go to the movies and see The Soiling, which promises to be the scariest werewolf film ever.
Roger paces around the attic, watching his sea monkeys grow in a flower vase. In celebration of their birth, Roger opens a bottle of champagne and then shares a drop with the sea monkeys. The drop instantly kills them.
Francine asks Stan for five-thousand dollars to open her muffin kiosk in the mall. Stan calls it a terrible idea. Klaus tells Francine that if he had a body, he would buy her the kiosk, amongst other things.
On their way home, Steve and his friends are talking about The Soiling. Steve is jumped by a wolf and is afraid that he might turn into a werewolf during the next full moon.
Hayley sneaks into the construction site at night hoping to damage the construction equipment. She's met by another group of extreme conservationists, whose leader Arborious, is buried waist high in a pot and believes he is a tree trapped in a man's body. Hayley agrees to join their fight against the mall expansion.
Roger holds a service in the woods for his departed sea monkeys. Suddenly, a wolf comes out of the woods. Instead of seeing the danger, Roger sees a new pet and starts to lead the wolf home by using Francine's muffins.
Stan uses the last of his bonus to buy a pair of rocket boots. However, the clerk tells Stan that he's about five-thousand dollars short. Stan is confused but then hears that there's a new muffin kiosk opening. Stan thought that he had talked Francine out of opening the kiosk, but Francine tells him that her muffins are selling well. Stan demands his five-thousand dollars back and Francine opens the register and hands it over. Stan is amazed she's made so much money so fast.
Hayley and the environmentalists are making their plans to stop the mall expansion. Arborious tells Hayley that to prove her loyalty, she needs to make out with a tree.
At the Smith house, Steve's friends tie him up to make sure that he doesn't transform into a werewolf overnight and harm anyone.
Stan is mad that Francine didn't leave dinner for him, and macaroni and cheese proves to be a challenge for the top CIA agent. Klaus tells Stan that he used to be a great cook and if Stan put Klaus's brain back into a body, he can cook for him.
The wolf breaks free from the attic and sneaks outside to maul a stray dog. The wolf jumps back in through Steve's window and onto Steve's bed. While Steve is sleeping, the wolf shakes off the blood all over Steve and his room.
Stan takes Klaus to the lab and performs the brain transplant.
Steve wakes up and sees blood and paw prints all over his room. He still thinks that he is becoming a wolf every night.
Stan brings the new Klaus into the kitchen, his brain is now in the body that belonged to the lead singer of an Earth, Wind and Fire cover band. Klaus hits Stan over the head with frying pan and flushes his old fish body down the drain. Klaus ties Stan up in the kitchen before he heads out on the town to update his look. He goes from soul man to a slick playboy.
Steve tells his friends that he's a werewolf and he has taken a life after seeing the blood in his bedroom. He tells them that they have to kill him to prevent anymore harm.
Klaus heads to the mall and buys all of Francine's muffins so she can join him for dinner. Klaus tells her that he's more interested in her business thoughts, than her body. Francine doesn't recognize Klaus' voice. In the food court, Klaus says all the right things to win Francine.
Steve and his friends meet in the woods and prepare to kill Steve in order to stop him from becoming a werewolf. At the same time, Roger, dressed in a Santa hat, pulls the wolf into the woods and poses for a Christmas photo. When the timer on the camera goes off, the flash scares the wolf, who breaks its leash and heads over the hills.
Stan charges through the mall, gun in hand, prepared to kill Klaus. Stan confronts Francine and Klaus and reveals to Francine that the man she has been talking to is Klaus in a new body. Before they can go any further, Arborious and his group declare that they have a bomb and plan to destroy the mall.
Steve holds a gun loaded with a silver bullet and tells his friends that they're all worthy of killing him, but only one can. The boys struggle over the gun and in the process knock Steve down a hill. Steve's unconscious body rolls down the hill and collides with Roger's loose wolf. The wolf dashes back up the hill, and the boys think that Steve has transformed. The wolf snarls at them and then dashes away. Snot fires the gun blindly at the wolf, which runs down the hill unharmed. Steve wakes up and climbs back the up hill, believing the curse has been broken.
Arborious preaches to the mall shoppers that American is destroying nature, and Hayley pleads with him to stop. But Arborious detonates the bomb anyway. Then he destroys a giant Native-American statue in the center of the mall. It topples towards Klaus, Stan and Francine. Klaus ducks for cover, while Stan pushes Francine out of the way to save her life. Francine realizes that Stan would die for her and that Stan truly does love her. Klaus' however, is pinned under the rubble, his new body destroyed. Francine sees a solution, a tank full of goldfish in a pet store.