Fred is experimenting with a giant chicken to try to get Harry back to normal size. Meanwhile Idella is jealous because Harry is spending a lot of time with a female fly. Idella flashes back to when Harry and her were young lovers and Harry was leaving for Vietnam. Idella is about to murder the fly when it flies into a window and dies. Idella and Harry make up at the end of the show and Fred disposes of the dead fly.

Tina has a big date and wants to borrow Ike's leather jacket. He refuses but she persists. They're arguing in the andromeda chamber when Turner locks them in. The experiment starts and they motion to Fred to get Turner, who is asleep and dreaming of bunnies and ice cream. Turner can't remember the numbers he pushed to lock Ike and Tina in, but Tina realizes that they were the numbers from his favourite song. They get out in time for Tina to go on her date.

The Pratts, the Edisons' yuppie neighbours, stay at the mansion when they get their house renovated and make themselves a pain in the behind. Casey has hostile feelings towards them and dreams of experimenting on them, but Fred and Casey and too scared to kick them out. So Harry takes it into his own hands and scares them out of the house, but only Ike and Turner know what he did. Throughout the show Harry is carrying out conversations with ants.

Fred is spending so much time with his guiney pig Fats that he neglects Casey. Casey finally gets over her inhibitions and tells Fred exactly how she feels about it. Fred is really distraught and goes to his barber for advice. Tony suggests finding the one thing that will make Casey feel special, so Fred buys a home dance kit and sings Casey an ear-splitting rendition of ""When a Man Loves a Woman"". They end the show in each other's arms.

The show starts with Tina politely telling her date that she doesn't really like him. Turner's tooth is loose, and Fred is out buying popcorn for the big movie ""Tara, Tara, Tara"", a TV remake of ""Gone with the Wind"". Fred misses most of the movie because he's putting Turner to sleep, but it turns out to be no great loss. Turner dreams that he's visited by the Sandman (a boring comedian), the tooth fairy (an Englishwoman) and Mr. Coffee (who is in the middle of a messy divorce). The show ends with a monologue by Uncle Harry.

Fred is playing around in the living room when Lenny Orca, Harry's long-lost boxing twin brother from Canada, comes to the door. Lenny tells the family that the reason he's taken so long to visit is that he's come home to die. He's OK with it, and the kids are too, but Fred, Casey and Idella are very concerned about it and decide not to tell him about Harry because it might kill him. He finds out anyway, but the doctor phones and tells him that he's not going to die. He promises to visit again at Christmas, gives the kids loonies, and makes up with Harry for an incident at the orphanage.

A gangster boss just got out of prison so he sends his two stoolies to look for the guy who ratted on him, Harry Orca. Turner lets them into the house by mistake, and they hold the family hostage and almost kill Harry. Richard comes over to complain about an illegaly-parked car but he leaves without realizing that the family is in danger. When the gangsters can't bring themselves to kill Fred, Idella takes the matter into her own hands and chases them out of the mansion right into the arms of Richard Pratt and two policemen.

When Fred's experiment fails he gets very depressed and flashes back to his graduation when Casey gave him Success and Failure stamps. The rest of the family is singing the Edison Family song. Richard comes over and tries to convince Fred to move to Tacoma. The real-estate agent comes during dinner, and the family is shocked that Fred wants to move. Fred passes out and Casey chases the agent out of the house. To comfort Fred, Casey brings down a letter he wrote her 16 years ago. The show ends with everyone, including Fred, singing the Edison Family song.

Ike wants to see a scary movie that his family won't let him see, so he goes with Turner. Turner is scared out of his mind. During the night, Harry gets caught in a spider's web and Turner is the only person there to get him out. But he's scared to touch the spider since there were giant spiders in the movie Ike took him to see. He finally gets over his fear and picks up the spider just in time to save Harry. On Tina's suggestion, Ike's punishment is having to take Turner to every Saturday matinee for the next six months.

Tina wins an essay contest and the vice-president plans to visit the mansion to celebrate. The guy that Tina invites to dinner is an environmental activist who wants to spraypaint the VP green. Tina dreams that she's on America's Most Wanted after they spraypaint the VP. A Secret Service agent comes over, however, and tells the family that he's sorry but the VP won't be able to make it to the mansion after all. Tina tells Ryan that spraypainting someone to make a statement is stupid and she wouldn't have done it anyways.

For Fred and Casey's 16th anniversary, Fred goes to the mall and gets her two tickets to see her old band-mate Jaz Pope. The family watches a video of Casey and Jaz to see what she was like. After Jaz' performance, which really stunk, Casey is debating whether or not to tell Jaz the truth about how bad her music is. Casey decides not to, and Fred, who Jaz thinks is Casey's old boyfriend Snake, doesn't help either. Jaz comes over to the mansion and she and Casey give a concert to the family.

The family is making plans for a trip to Hawaii, but Ike is told by his teacher that if his next essay isn't good enough, he will fail Social Studies and have to go to summer school, which would make the trip impossible. But he can't bring himself to tell his family. After a nightmare he finally tells. The family is mad at him, but support his essay, which he thinks is good enough to pull off a passing grade. The show ends with the family lying in the sand relaxing and listening to the sounds of the ocean... on the back porch.

The family is worried whether Uncle Lenny will make it to the mansion for Christmas because of a big storm that's predicted. Kiefer tells Turner that Santa Claus doesn't exist. Meanwhile Lenny's dogsled gets snowed in, he hitches a ride on a plane, falls off it and collapses in the snow. Turner goes to sleep asking Santa to forget about all the presents for him and to help his Uncle instead. Santa comes to Turner (in a dream?) and takes him to where Lenny is lying in the snow and they bring him home for Christmas.

The parents of Dexter, a guy in Tina's class, convince him that he must defeat her academically, so he comes over and plants a virus in her computer. Her computer is hooked up to the computer in the lab, so when Fred tries an experiment on Buck it turns him into a mutant monster. Dexter, who is torn between his crush on Tina and his parents' hard line, goes to the mansion to confess what he's done. He has an argument with his parents through the closed door, and finally his family agrees to stop pushing him so much. Dexter fixes the virus he put in the computer so Buck is turned back to normal.

Idella tells Harry that she misses their old relationship. He is distressed and asks Fred to turn him into a giant fly to save his marriage. Idella is delighted, but every time someone comes over to the mansion Harry has to hide since he still has giant wings. He's sick of all this hiding, and confesses how he feels. Idella finally accepts that Harry was happier as a fly, and they decide that Harry will be shrunk back. The show ends with Idella deciding to share the cooking for the family.

Fred goes to the a meeting of the L.L. Edison Corporation, the company that his grandfather founded which he has to go to once a year to sign a bunch of forms. The new board member Totterton is forgetting the Edison values and only working for money. Idella suggests that Fred call his father, but Fred wants to solve this problem on his own. Idella comes to a meeting and gets Fred to sign all his shares to her, then denounces Totterton. Her and Fred convince the board to return to the company's old values. To celebrate the family orders from the Taiwan On and Fred's father comes over and tells Fred he's proud of him.

Ike is being mean to Turner and Casey yells at him when he puts his man in the toaster so he goes up to his room to play with his dollhouse. Casey comes up to talk to him and they make up but Tina bursts in and yells at him about her tape. Idella reads a letter from Lenny to Casey. Turner is really upset and dreams about him being the boss. All his kids are bothering him so he learns how tough it is to be a parent. He apologizes to the family, and at the end of the show he is made King of the House for 44 minutes.

For Tina's '60s dance Fred is going to teach her the twist, but the record is broken in two. Fred and Casey automatically blame the kids, and try to find out which one did it. Someone comes down during the night and replaces the record with a new one. The adults lecture the kids about the record, and trick Tina into confessing to replacing the record, but not to breaking it. Then Turner says he broke the record but he really didn't. It turns out the record was broken by an explosion from the lab, so Fred and Casey owe the kids and apology.

This episode is done live, in front of an audience in Toronto. Fred's too sick to go to the zoo but the family doesn't seem to mind. He gets depressed about this, collapses and dies and spends the rest of the show observing how the family responds to his death. The lights switch back and forth between Fred and the family and weird things keep happening. Then all the lights go out and the family comes back to find Fred lying on the floor. His death was just a dream. Needless to say, the cast is not happy with how the show turned out and Fred blames the whole thing on the producer.

Idella is telling Tina about the romance in Europe because of Tina's class trip that she's going to take. Tina is in the closet and overhears Casey telling Fred that because of a hair disaster their collaboration on experiments is over; Tina thinks that they're talking about their marriage being over. She dreams of a long Spanish Flamenco dance scene with her, Fred and Casey. Then she's a Gondolier taking Fred and Casey to a bridge of love. Then the family starts singing opera. Tina wakes up, sees Fred and Casey make up and says she's never felt better in her whole life.

Fred and Tina finally discover a way to get Harry and Turner back to normal. Turner doesn't really want to be small, Casey doesn't really want it either because Harry and Idella are going to move out. Turner and Harry are put in the chamber for the final time, but, as Ike points out, they forgot the ball. When the experiment is finished, the family takes one look at Turner and Harry and scream their guts out. The director yells ""cut"", the season ends, and the party starts. Everyone is different at the party: Idella talks with a Caribbean accent, Fred is a pompous baboon, Lenny is a boor, Turner is going to the desert with a biker gang, Harry is planning to do a fishing show, Casey is a total ditz who's going to do a show in Venezuela, Ike's voice is changing and Tina is overeating. Fred is thinking of leaving the show, but gets up to give a speech and breaks down. He decides never to leave because Maniac Mansion is his family. Everyone starts clapping, then Fred wakes up, and

Harry is stuck inside the mansion in a parody of Home Alone. Most of this episode is Fred explaining what Maniac Mansion is about. He tells stories of pilot episodes, and how the show developed from there. He then meets Casey and Idella, and finds out that the script has changed so that only Harry is in it. He's angry and tells Ike and Turner that they have to write themselves into their own script. Later, Tina comes by and makes him realize that the show is about everyone through flashbacks of the first season. At the end, the family decides that they need to make it look like a television show again. They have Fred wake up from a nightmare about his family being a TV show, as they sometimes did in the first season.

Casey complains about how the living room looks, and wants to redecorate it. Fred doesn't want to, but eventually gives in and tells Casey to go ahead. Fred flashes back to his 18th birthday, and remembers how happy he is with the living room. The movers come to get the couch, but on the way out Turner jumps on it. Casey tells him that they'll keep the furniture, but gives Fred a lecture about how selfish he's being. Fred then flashes back to his birthday when he was drafted. He then decides that the family should make their own history as a new generation of Edisons. The show ends with everyone enjoying the furniture Casey picked out.

Harry watches a talk show that Idella hates. She tells him that he has as much talent in him as all of their guests put together. This inspires him to go down to the studio where the show is taped. When Lanny Reese (the host) realized who Harry was, he trapped him in a glass. The family was worried about where Harry was, and they though he was dead. That night they watched the Lanny Reese show and saw Harry trapped. Harry pretended to be dead, and flew out when Lanny lifted his hand off of the glass. He made his way home, and the family was glad to have him back.