A pack of Wildlife Explorers are in the woods, gathered around a campfire at night. They're complaining that one of their members, Martin, has eaten all of their breakfast supplies. Martin insists that a baby bear got ahold of their food, even though one of the other Explorers, Huey, has photos of Martin eating the cereal. Suddenly a creature pulls Huey into the woods. The campers hide but the beast comes after them one by one, chasing them out of the woods. They barricade themselves in the pack leader's car and wait until morning... and wonder what happened to one of their members, Eddie Munster.
At the campsite, a naked and confused Eddie emerges from the woods.
Sometime later, a real estate agent takes Marilyn Munster to a home on 1312 Mockingbird Lane. He tells her that the house is bright and cheery and gets lots of sun, but Marilyn tells him that sunlight isn't a part of her family's future. She notices an abandoned manor across the street at 1313 and asks the agent about it. He warns her that the owner used to poison hobos and that it's a horrible place, and Marilyn says that they'll take it.
Marilyn, her uncle Herman, and Eddie soon move into the house. While Eddie and Herman look around, Eddie wonders why they're moving. Herman says that it's just a coincidence that they're moving at the same time that a baby bear attacked the Explorers, and that it will probably follow Eddie in 29 days when it regroups. They discover that there is a secret passageway beneath the main staircase. As they look downstairs, Eddie tells his father that Grandpa said that he had a condition, the same condition as Marilyn. Herman tells him that it's probably cleared up, but Eddie says that he likes being normal. Upon hearing that, Herman put Eddie's hand on his chest and says that his son got his condition from him. Eddie wonders what part of his body and Herman says that his heart is how he remembers who he is because he's stitched together from so many people.
Marilyn goes into the conservatory and is delighted to find a dead tree in the center and crows perched on the branches.
That night, movers Garcia and Perez deliver two refrigerated crates to the house. As they unload the first one, Perez drops it on a corner and rats pour out of the box. The two movers panic and drive away, while the rats merge into the figure of a man. Marilyn comes out and tells Grandpa that he needs to put a robe on. Lily, his daughter, transforms into mist and leaves her crate, and then has spiders weave her a dress as Herman comes out to greet the rest of his family.
After making love, Herman and Lily talk about Eddie's condition. Lily worries that she didn't breast-feed Eddie and bond with him, but Herman assures her that she couldn't love Eddie any less. He warns her that Eddie is starting to ask questions and Lily doesn't want her son to know what he really is. She thinks that Grandpa should talk to Eddie but Herman doesn't think that's good idea. As they talk, Herman's heart loses a staple and Lily warns him that he's stressing his heart by loving too hard.
The next day, the Munsters gather for breakfast and Herman tries to make small talk with Eddie. Eddie isn't buying it and is wearing his Explorer uniform for his first day at school so that he can have some structure. Grandpa assures Eddie that there's nothing wrong with him and he shouldn't talk about that kind of shame. Lily assures Eddie that they'll love him no matter where his hair grows on his body. Herman and Grandpa argue who will explain it to Eddie, but are interrupted when the bus arrives. Eddie goes out to the bus without saying goodbye and Herman goes after him. His son is aware that he's lying to him and gets on the bus. When Herman starts to go back inside, his heart gives out and he collapses.
That night, Eddie mounts a lightning rod on the roof and Grandpa uses the resulting electricity to bring Herman back to life. Grandpa tells his son-in-law that he broke his heart and starts to throw it away, but Herman wants him to put it back in because it's the last part from his original body. Grandpa still wants to tell Eddie the truth, telling Herman that he can't understand because he isn't a Munster by blood.
The next day, Grandpa and Marilyn walk up to the street and Grandpa is unhappy that the neighbors are too close. Marilyn suggests that he use good manners and Grandpa tells her that he's going to make cookie. However, he secretly adds a bit of his blood to each one. They then go visit the next-door neighbors, Marie and Tim. Marie knows all about the "hobo house" and refuses to let them in. Tim is much happier to see them and eats one of the cookies. He falls under Grandpa's hypnotic spell and he argues about the fact that Marilyn is planning to move in with them despite her "condition." He warns Marilyn that he may start "drinking" again if she stays, but she insists that she belongs with the family. Once they finish, Grandpa takes Tim out of his trance and convinces him to invite them in freely and of his own will.
That night, Eddie, Herman, and Grandpa go to the school meeting for the Wildlife Explorers. The pack leader, Steven, is very very enthused about outdoor camping. He wonders which pack Eddie was with before but Herman hesitates to tell him at first. He finally admits that Eddie was a member of the pack that the baby bear attacked. As they talk, Lily arrives and every male in the crowd stares at her, including Steven. Grandpa notices his reaction and how it makes his heart skip a beat.
The next day, Grandpa and Marilyn take Eddie to a hunting blind in the nearby woods and watch a deer. They start to explain about the circle of life and how everything kills something else to survive. A mountain lion kills the deer and Marilyn tries to convince Eddie that it was depressed and wanted to die. He isn't very convinced. When Eddie wonders what kills the mountain lion, Grandpa turns into his demon-bat form and kills it, and insists that it's all a part of nature.
Later, Lily finds Eddie sleeping in his drawer and tries to reassure him. She tells him that people like "baby bears" and that they're just confused and misunderstood. The talk turns to eating and Eddie wonders if his mother could eat someone. Lily admits that eating people is part of her nature, but she says that she does her best not to do it. Much to her distress, Eddie says that he's glad he's not like her.
When Herman hears about Grandpa's "lesson," he goes out to confront his father-in-law. First he asks why Tim is painting their house, realizing that Grandpa has made him a blood slave. However, Herman would rather talk about Eddie, warning Grandpa that he's a sensitive boy. Eddie and his heart are the only two things that Herman has that he can call his own. Grandpa reminds his son-in-law that his heart will soon give out and that they should use Steven for a replacement since he's attracted to Lily. They're interrupted when an exhausted Tim falls off the ladder and collapses. They call the paramedics and Marie comes over. Grandpa tries to comfort her without much success. The paramedics revive Tim and Grandpa complains that Herman called an ambulance and wasted a perfectly good heart.
That night, Grandpa invites Steven to dinner. After making sure that Steven has no immediate family and no one knows he's there, Grandpa suggests that Steven open his heart to new possibilities. He tells the pack leader that Herman is dying of a heart condition and that he doesn't want to leave Lily and Eddie alone. Steven figures that he's talking about marriage rather than an involuntary heart donation.
At dinner, they talk about the value of family and Herman realizes what Grandpa is up to. Lily asks to talk to her husband alone and asks why Steven is there. Herman admits that they were considering taking Steven's heart and replacing Herman's with it, and Lily doesn't want Eddie to know about it. She wants Herman to tell Eddie what he really is because she can't bear the look he'll give her when Eddie realizes that he's like his mother. Herman says that he doesn't have the heart to do it, showing Lily his damaged heart, and says that he doesn't want his son to feel different about his parents. Lily assures him that she's willing to feel different as long as they all feel different together as a family.
At the table, Steven notices that no one is eating and Eddie tells the pack leader that he's a vegetarian. Grandpa reminds him that the Munsters have always been meat-eaters and tells him to eat his meat before he can have vegetables. Eddie plays with his food and tells Steven that Grandpa ins going to eat him, and Grandpa blows off the accusation. Herman and Lily come back and, overhearing, assure Steven that no one is going to eat him. He decides to make a hasty and Marilyn escorts him to his door while Herman goes to talk with his son and Lily talks to Grandpa. However, Grandpa slips away when no one is looking.
Marilyn gets Steven to the door and tells him to run. However, Grandpa is waiting outside in his demon-bat form. As he advances on Steven, the secret passage in the stairway opens behind him. When Marilyn tries to push Steven into running, she accidentally shoves him down the secret passage's stairs.
Up on the roof, Herman talks to Eddie and finally tells him that he's the "baby bear" that attacked the Wildlife explorers. However, Herman assures his son that he's not a monster and that all he did was become a werewolf. Eddie doesn't think there's anything worse but Herman tells his son that he has nothing to be ashamed of and says that he doesn't want to be a Munster. Herman promises that they'll make sure he doesn't harm anyone and deal with his problem when it happens again, but Eddie runs off without a word. As Herman looks after his son, his heart finally gives out and he slides off the roof.
Later, Herman wakes up and finds himself in the lab lying next to Steven's corpse. Grandpa has transferred Steven's heart to Herman's chest and is sipping the leftover blood, leaving him much younger looking now that he's had a proper meal.
Sometime later, Herman becomes the new pack leader. He and Lily take Eddie out and tell him that they've arranged for him to have a pet that will keep him for hurting anyone. When Eddie says that a dog can't do that, they tell him that they have something better... and a dragon flies down to greet its new master.