Ned goes to the pet store, hoping to buy an elephant, but all he can afford is a listless newt he called "Newton" who does nothing but sit in a fishbowl. The pet store owner sells him a can of Zippo For Newt, which turns Newton into a 6-foot transforming anthropomorphic newt. Ned and his new pal, Newton, trash the house by playing Tag.

Ned has a crush on the girl across the street, Linda Bliss, but can't talk to her. Newton tries to get her attention by throwing a tiny pebble against Linda's bedroom window while she's asleep, but ends up throwing a boulder, and destroys the window. Ned and Newton desperately try to replace it before Linda wakes up the next morning.

Ned's class are making small floats for the annual Friendly Day Parade, and Newton wants to help. He ends up making an enormous, barge-sized float for Ned and ruins the parade when the float causes massive property damage and sinks in the lake.

Ned's tattletale cousin Renfrew comes to visit. He destroys most of Ned's toys and repeatedly tells on Ned. Newton decides to drive Renfrew away by causing a series of ridiculous situations, which causes Renfrew to have a nervous breakdown as he tattles to Ned's parents about them.

Ned is sent to the grocery store to get a can of tomato paste, but Newton instead suggests they go to Mars, thinking that it's made of tomato paste similar to the idea that the Moon is made of green cheese. They go to Mars, and it is made of tomato paste! But they find that the tomato paste there tastes awful, so they decide to just get it from the grocery store after all.

Ned attends Boy Scout camp, and Newton notices that the other scouts have more merit badges than Ned. Ned doesn't care, as he's allergic to the outdoors and doesn't enjoy being a Boy Scout, but not wanting to see his owner disgraced, he motivates Ned to earn as many merit badges as he can. Eventually, when Ned becomes the most decorated Boy Scout, Newton decides to wrap the entire forest in anti-allergenic plastic, but when he does, Ned finds out that he wasn't allergic to anything in the forest, but to his mother's macadamia-nut cookies that she always packs him.

In another attempt to get closer to Linda, Ned plans to audition for a school production of "Little Red Riding Hood". Newton, eager to help out, wants to be cast as the Big Bad Wolf. Unfortunately, the new school drama teacher is an ex-Hollywood executive who makes Ned and Newton repeatedly change the play until it's a post-apocalyptic science fiction story called "Mad Max and the Chicken-Wolf", where Linda isn't even in it.

Ned has been watching too many monster movies, and when he's left in the house alone, he's paranoid that there are monsters around the house. This isn't helped when his parents ask Uncle Frank and several friends of his to check on him, and they're all dressed as monsters, on his way to a costume party. Newton, after thinking about what killed all the monsters in the movies, decides to let the monsters fall to their death by jacking up the house and pushing them out the door.

Ned's father opened a new bank account for Ned, after finding all the change around Ned's room. To Ned's horror, however, that means he has deposited his "lucky penny", a treasured penny that has an image of Gene Hackman as Lex Luthor on it. When the bank refuses to get it for him, Newton helps Ned by breaking into the bank vault to find it. They do, but Newton had to give away $3.5 million in the bank vault to make it easier to find. They're saved, however, when a passing coin collector points out that Ned's penny is only one of two in the entire world, worth $3.5 million. Ned and Newton quickly put all the money back in the vault, and the bank owner gives Ned the only other Gene Hackman penny in existence.

Ned's family is on a long, boring car trip, with only a "Vehicle Bingo" game to pass the time. Ned's parents accidentally leave him at a rest stop, however, and Ned needs Newton's help to catch up to them. After being blasted off to Russia, they end up traveling around the world and take every mode of transportation on the Bingo card trying to get back, which perplexes Ned's parents.

Ned goes with his dad on Take Your Child to Workday, and while he initially thinks his dad's job is dull, he eventually thinks that his dad is a government spy, and tries to find out more information.

When Ned complains that he can't go to summer camp, Newton mistakenly thinks he's describing boot camp. He signs Ned up for the army, and while no one notices that he's 10 years old and insists he does basic training, Newton tries to find a way to get him out.

Ned decides to climb a small hill to raise money for charity, but Newton thinks he would raise more if he climbed Mount Everest, so he takes Ned there and helps him climb it.

Winter is coming, and Newton learns that newts hibernate during the winter, a process he doesn't want to go through. When he learns that birds migrate instead, he decides to go away for the winter and takes Ned along.

Ned and his family are all set to spend a weekend in exciting Gamble City, but when Ned's mother finds out there's gambling there, she decides to have Ned stay with his aunt and uncle instead, who is a depressed, puritanical Eastern European couple who think fun is unhealthy. As Ned and Newton become more and more bored, Newton decides to have the whole house shipped to Gamble City.

Ned was born on New Year's Day, and as such, is expected to play Baby New Year every year at a New Year's Eve pageant. He doesn't want to do it at his age, so he desperately tries to find out if another New Year's Baby has been born in the town, saving him the embarrassment.

Ned's been given a small role in a horror film "Car-Driving Trees of Egstappa Part 2", but soon finds out that the Car-Driving Trees are real, and plan to wipe out Friendly Falls.

Ned and his friends are collecting 10,000 bags of pet hair for charity, but Ned's cousin Renfrew wants to sabotage their efforts. Newton will have none of it, so he attempts to get Renfrew off their case.

Ned comes with his parents on their anniversary cruise, but thanks to Newton, he ends up on the wrong boat.

While Ned is working at a TV station, Newton accidentally destroys all of the station's pre-recorded content for the weekend, and he and Ned have to record all-new footage to replace it. They re-enact the news, several TV shows, and try to splice in whatever spare footage they can find to fill time.

When Ned's parents hear him talking about Newton, they assume this is a new imaginary friend, similar to one Ned had in his early childhood, a big talking red shoe named Shoe. They take Ned to see a child psychiatrist, but when they accidentally see Newton who has been going out and around in the form of a shoe since he found out about Shoe, and assume that Ned's imaginary friend is visible to them as well, they also go and see a psychiatrist. In the end, it turns out Shoe is real.

With Mother's Day approaching, Newton thinks the purpose of the holiday is to give your mother as a gift. He finds his mother and proceeds to give her to Ned.

Ned has started keeping a diary, but his entries are very typical and boring. To spice it up, Newton starts causing increasingly exciting things to happen in Ned's life so that he will have more to put in his diary.

Ned's class has started learning fractions, which Ned has difficulty with. To help him grasp the concept, Newton splits himself across the middle, but his lower half develops a mind of its own and tries to run away.

The carnival is in town, and Ned wants to take Linda to it. He's terrible at most of the carnival games, however, and Rusty McCabe beats him at all of them. Ned finds out later, though, that Rusty's uncle owns the carnival, and has rigged all the games to take the visitors' money and let Rusty win every time.

Ned sends in 20 cereal box tops to get a "Captain Ocelot Crypto-Claw" toy, but when it doesn't come for eight weeks, Newton decides to go and find it. After going through the company that makes it, they find out each of the toys is manufactured by a goat named "Inchina", and the box tops are meant to feed her as she makes each toy, which takes up to eight weeks.

Ned is excited to go to xylophone camp, but is dismayed to find out that no one there actually plays the xylophone, and that it's meant to be a camp for all the kids that couldn't get into "fun camps". After seeing that everyone is wasting their time on an electronic toy called the "Battery Drainer" because of its flashy commercial, Ned decides to create his own commercial to get the other kids interested in playing the xylophone.

Ned has to do a local history project for school, but all of the good topics are taken. He soon finds out about the Friendly Triangle, an area in town where things allegedly disappear. He gets several eyewitness accounts of paranormal events in the Triangle, but when he tries to investigate them, he finds out all of his witnesses were just from a family with very poor eyesight that lost their things, and that the Friendly Triangle isn't real.

Newton is worried that when Ned grows up, he will get rid of him. When he learns about the story of Peter Pan, however, he decides to take Ned to Neverland, where he won't grow up. Through a comedy of errors, however, Ned and Newton instead uncover an unlicensed video distribution operation.

Ned's parents all go up to a cottage in the mountains, owned by Renfrew's parents, for some "peace". Renfrew's parents, unfortunately, are foley artists, and decide to catch up on some work while they're there. Things are made worse when Ned has to deal with Renfrew some more and gets lost in the woods while trying to re-enact the stories of fictional nature hero Woodsy Foreston.

While on a field trip to the zoo, Ned and Newton decided to go to the bus through the emergency exit in the back. However, they find out that this door is actually a portal to a parallel universe, where the bus is parked in a lot of identical buses. They have to find the right one to get back home.

Ned's parents lose all their money on a crooked insurance policy to insure several "valuable" things around their house, including a Gene Wilder bedroom mirror and a broken "unbreakable" vinyl record. This policy will only pay out if a series of impossible things damage these items, so Ned and Newton work together to destroy these items in impossible ways, get the money back, and thoroughly confuse the crooked saleswoman.

Ned gets a virtual pet toy, which makes Newton jealous. Soon, though, Newton finds out that the toy has artificial intelligence and intends to conquer the world. He tries to convince Ned that the toy is evil, but he doesn't believe him, assuming that he's gotten more jealous. It's up to Newton to defeat the evil virtual pet on his own.

Ned has been made the coxswain of the Friendly Falls rowing team in a regatta against the neighboring town of Carty Garbageton, a filthy town founded by janitors and gas station attendants. Friendly Falls traditionally beats Carty Garbageton, by coming in second-last. Their "winning" streak is in trouble, though, when Friendly Falls loses all its money sponsoring a start-up company to sell smoke and soot from the town's old chimney factory. Many of the townspeople have to do menial work in Carty Garbageton to make the money back, but they're all fired when the town starts becoming clean. Ned then gets the idea to sell the soot to Carty Garbageton, and the town makes all its money back just in time for Friendly Falls to not come in last at the regatta.