While watching TV, P.J. and Max see the trailer for a newly-released horror flick, The Mutilator on Main Street: Part 7, which Pete encourages P.J. to go see, thinking it will make a man out of him. However, Goofy is at first reluctant to let Max go and see it because scary movies frighten Max and give him a bad case of the hiccups. However, after Max insists that nothing scares him anymore, Goofy lets him see it with P.J. Unfortunately, the movie proves to be scary enough to traumatize Max, with Max giving him hiccups.
Meanwhile, Goofy heads out to do some evening grocery shopping, nearly running over Pete in the process. As Pete proceeds to head back inside his house, he bonks his head on a branch growing over his yard from one of Goofy's trees. He yells at Goofy for having not yet cut that branch down.
Later that night, Goofy returns home to prepare himself a sandwich while Max and P.J. exit the movie theater. The formerly nervous P.J. expresses how awesome the movie was while Max pretends that the movie didn't scare him. After some creepy noises in town spook the two, they run home to find Goofy making his sandwich. Goofy suspects Max to have been scared by the movie, but Max tries to deny it. Too afraid of spending the night by himself, Max asks P.J. if he'd like to spend the night. When P.J. calls Pete to ask permission to stay over, Pete cruelly jokes that the movie is based on a true story, and that the real Mutilator is on the loose. Later, Pete decides to have some fun scaring P.J. and Max by pretending to be the Mutilator.
Pete goes over to Goofy and Max's house and begins to make all kinds of noises, scaring Max and P.J. When Pete peeks into Max's bedroom window and lightning crashes, the boys think he's Mutilator having come to get them. They inform Goofy about the noises, who then decides to go and investigate. Goofy is accidentally locked out of the house and, while he tries to find a way back inside, the boys soon think he is the Mutilator.
When Peg catches Pete sneaking in and finds out he was out scaring the boys, she makes him go back and apologize. When he sees Goofy covered in mud, he becomes scared and accidentally hits his head on the same overhanging branch of Goofy's tree and knocks himself out. When Goofy tries to get back inside by climbing up the side of the house, he accidentally cuts the phone line. With the phones out, Max and P.J. try going next door to call the police, but then spot the unconscious Pete sprawled on the ground and mistake him for a dead body. They run back to Max's house and board up the front door. Meanwhile, Goofy enters the house through the basement window. As he stumbles around in the darkened basement, Max and P.J. think it's the Mutilator down in the basement and run up to hide in the attic.
When Goofy gets stuck in the basement, he uses a chainsaw to cut down the door to the kitchen. He then goes to the refrigerator to make a replacement sandwich after Waffles ate his first one earlier. Goofy falls back down into the basement after slipping on some of the food he dropped on the floor. Max thinks the Mutilator has got his dad and goes down to rescue him. When they see a shadow move across the living room, P.J. and Max throw a blanket over Goofy, thinking they've caught the Mutilator. As the boys proceed to beat "the Mutilator" with a tennis racket and a fly swatter, all three of them fall into the basement. P.J. flips on the light switch, and it is revealed to the boys that the so-called Mutilator is actually Goofy, who tells them that there is no Mutilator!
As morning dawns, Max and P.J. find out that the "dead body" under the tree was actually Pete. Outside, Peg wraps some gauze around Pete's head in the front yard before Goofy shows up wearing a welding mask and carrying a chainsaw. Pete thinks it's the Mutilator and jumps up in fright, only to hit his head on the tree branch yet again. Goofy then proceeds to finally cut off the branch with the chainsaw.
- When P.J. says the Mutilator ate Goofy's cat, Waffles, the colors on his mouth and tongue were mixed up.
- When Peg is awake after she hears Pete cackling and laughing, she's in the same pink shirt instead of her lavender pajamas.
- The Mutilator is based on Jason Voorhees of the Friday the 13th series of horror films, while the name of his film series, The Mutilator on Main Street, is based on the A Nightmare on Elm Street horror film series.
- The Evil Queen from Snow White and the Seven Dwarfs is mentioned.
- This is the only episode in the series to have a fully original, scene-specific music score (rather than reusing multi-purpose music cues as subsequent episodes do.) Additionally, this episode's music score is composed by Robert Irving, rather than Mark Watters. This could be because this is the first episode in production order.
- Pete's reference of the Mutilator being a true story and how "he came in through the bedroom window" is a reference to the Beatles song "She Came In Through the Bathroom Window" on the Abbey Road album.