King

The Wright family moves to a new house and Russel discovers the passage to Under under his bed. He befriends Loopy and Vernon and together with Russel's dog Gus, they challenge Bob Wire for the crown of Under and Russel becomes Under's new King.

Bob sends a fake SOS to Russel from ex-Princess Populah so he can lure him into a trap and steal back the crown. Meanwhile Loopy hatches what he believes is an Urklet egg, only to find it was actually a vicious Rebbuloc, which terrorizes the throne room before escaping to Up and encountering Cliff, who was trying to sneak down to Under.

While trespassing in Near Under, Loopy is mistaken as a pet by Auntie First and she locks him away. When Russel goes to help, Gus is also taken and Populah has to help the King rescue his friends. After leaving for Near Under, Vernon starts work on Under's new currency: greenbacks, which Bob quickly began hoarding to himself.

By Russel's request, Vernon builds a car. Bob however steals it to bring to Auntie First as their new secret weapon for invading Under, leaving Russel and his friends stranded in the desert.

Russel orders the populace of Under to stop blaming the Pubrick for all their problems, not knowing that this will allow the creature to turn into a fearsome beast. Meanwhile, Bob commandeers Vernon's ripulator to create a fault around Under, ransoming the Crown in exchange for the key that will set things right and prevent Night Slythers from emerging at sundown and destroying everything.

When a stray dog keeps Russel up all night, he goes down to Under and finds everyone sending their garbage up to the moon and Gus with the crown are sucked away as well. When Russel goes to retrieve them, he learns from the Hermet who lives on the moon that one more load of garbage will send it crashing into Under next year.

Mysterious pollen flows from Under up into Russel's room, knocking out Cliff and sending Russel down to investigate with Gus. When they get rid of the bush responsible, Loopy discovers that a mass of unknown monsters are bearing down on the town.

Bob tries to trick Auntie into invading Under, eventually carving a Floating Mountain into the shape of Russel's head that motivating Auntie to build a giant wall. This forces the Gorbal Birds to fly to Under instead of to their normal roost in Near Under. This upsets Russel since the birds start pooping on his newly constructed Roller Coaster (which he built since he's too short to ride one in Up).

While doing some plumbing, Russel and his friends are sucked down to Under Under where the crown is eaten by a Slyther. They befriend her owner Hugh the Yu-Yu, who is living under a giant stalactite that is poised to fall at any moment. Despite Russel's insistence, Hugh refuses to leave since his Fuzzy Dice told him to stay.

Russel decides to practice for his Gopher Scout camping merit badge in Under. Vernon dislikes living off the land and sets up a big fancy forest camp for all the people of Under. Meanwhile, Bob steals Russel's scout handbook and tries to use its advice to steal the crown.

Russell learns to play Under's national game for the first time: Joustabout. But will his limited experience be enough when he faces Bob Wire for the crown title?

Russell dress up as his favourite comic book superhero to fight crime in Under.

A Frobish monster bites Cliff when he goes snooping in Russell's room, and Russell feels it is his responsibility to find the antidote before he becomes a monster permanently.

After accidentally turning Under into pumpernickel, Loopy runs away to be a pirate. Russel, Populah and Gus go after him and are captured by Loopy's new crew mates. Meanwhile, Vernon tries to stop Bob as he sends rock monkeys to eat Under.

Gus searches for the Everything Log, independently, in order to make a wish.

In order to make ice cream, Vernon and Loopy set up a factory with a blizzard inside it, causing the outside world to turn into a desert. When Russel decides to get rid of the ice cream in favor of the climate, Bob starts a coup. Meanwhile, Near Under is beset by the petrifying Hairy Eye-Ball, so Auntie and Russel make a deal to solve each other's problems.

Bob uses a monstrous Nossix to take over Under and steal the crown. Russel escapes and heads to the cruel Tower of Derision with Populah to read Great Great Uncle Zeb's advice on beating the Nossix. The Frags, having been outed by the monster, teach Vernon and Loopy how to indirectly disobey Bob's undesirable orders to stop Russel.

Faced with a riddle he can't solve, Vernon breaks down and Russel takes him to the Clockmaker to be fixed, only the Clockmaker won't cooperate, needing Vernon to keep time correctly in his town. Meanwhile, Loopy helps Auntie first stop Bob from demolishing Near Under as part of his "Wire Man" show.

Gus chases a cat to Under and she takes Bob hostage, using him to fly her away from Gus to Near Under, the dog and the Frags (who don't understand the dog-cat feud anyway, believing peace was better) in hot pursuit. However, Auntie First is waging a war with her Cousin Tess, the leader of Under Sea because they once wore the same dress to their school prom. Russel tries to stop the war since all the sea creatures are being forced to flee to Under due to it. However, once Russel saw that the dresses weren't actually the same, the evidence was destroyed.

Embarrassed by the prospect of trading party supplies to Hugh the Yu-Yu for her weight in Slyther Cheese, Auntie (and Bob) kidnap Loopy to make her his Lighter Than Air pastries. Unfortunately, without the trade, Hugh is faced with a giant rat attack, and Russel must step in to save the economy.

The mouse-like bandits start stealing things in both Under and Up, leading the Wrights to believe the house is infested by rodents. They then call an exterminator and Russel fears the passage to Under will be discovered, he is also blamed by Lou and his mother for the thefts.

In order to go river rafting, Russell has Vernon create a Veggi-Double clone to attend the G-4 meeting in his stead. But when a Giga Gut attacks Near Under, Auntie First, Cousin Tess and Hugh the Yu-Yu and Bob find "Russell" to be no help at all in finding a solution, until they are informed by Bob Wire that they were actually dealing with a clone.

When the Bluebird of Happenstance does its annual flyby to Under, it poops on Loopy bestowing him with bad luck and take off with Russel's crown, leaving a blue feather behind. Loopy locks himself inside a rollable glass ball to stop getting bad luck while Russel tracks down the bluebird. Meanwhile, Auntie causes her subjects to run away again to Under over an unfair "Light Tax" and has to rely on Bob to bring them back when he gets the crown from the bluebird.

When Bob loots the Uncertain City, he comes across three ancient urns. Auntie confiscated one with a freeze-dried Giant Nose (an extinct monster) which comes back to life and starts attacking the towns. Loopy buys an urn filled with ancient air from Bob and releases it in the castle, sending it and everyone inside back to prehistoric times.

Russel infects all of Under with his cold, turning them all into uppity superheros who kick Russel and Gus out of the town. Bob and Vernon, being inorganic were immune. They go to Near Under and Captain Darling tells them a plant native to the Equatorial Glaciers will cure the infected Underites, but Bob tells their plan to the Underites in an attempt to get into their good books. Vernon tries to find the cure for Russel's cold in Up.

Faced with a daunting school recital, Russel has a recurring nightmare about performing the accordian in front a hoard of monsters. In Under, the Dream Gulper arrives and materializes the dreams of its sleepers. Bob catches the Dream Gulper for his dream of being giant and ruling all the local kingdoms to come true. Russel has to confront his fears to reach the Dream Gulper and stopping Bob's dream from becoming reality forever at sunset.