Wander finds a sock left behind by someone, and is determined to find its owner. He and Sylvia face dangerous obstacles and challenges as they rush to find whoever owns the sock, though problems keep ensuing.
At the beginning, Wander and Sylvia are being chased by Watchdogs on a desert planet, when Wander suddenly sees a sock on the ground. After Sylvia fights off the Watchdogs, she asks Wander why he left her side. Wander tells her he found a lost sock and is determined to find out who it belongs to, much to her disapproval.
Later in the village square, Wander begins asking random people if they lost a sock. Sylvia then suggests him to go to the lost and found department. Wander is reluctant about this, but Sylvia assures her that the Lost and Found Guy will make sure the sock is reunited with its original owner.
Wander unwillingly hands over the sock to the Lost and Found Guy. Just before they leave though, the Lost and Found Guy then informs Wander of a guru who can answer any question including the owner of the sock. He warns them that the path to the Intergalactic Guru is rather perilous, but Wander is excited about this, while Sylvia is annoyed.
The adventure starts in the Grizzly Forrest, where Wander and Sylvia get chased by grizzlocks. They obtain a key from the Giant Hoarder Scorpion. The key unlocks the Tomb of the Unknown Emperor. In the tomb, they encounter the Fierce Tigrex of Nil. Wander tames it by scratching its back. Sylvia finds a map to the Farbrix Lavadrome. When they drop into the Farbrix Lavadrome, they save the fair Princess Galactica from Doom Dragons. Galactica leads them to the castle of the cobra ruler, Dragor the Destructible, since they have to obtain the Infinity Crystals from his throne. Wander distracts him by dancing, while Sylvia pries the crystal off with a crowbar. They then go to the Iceatorium, and rescue the unfair Princess Veronicron from similar Doom Dragons, but she is not as thrilled about the rescue. Later in a space canoe, they bypass a Solar Siren. At the Quicksand of Forgetfulness, Wander briefly cannot remember what they are doing, until he looks down and remembers the quicksand. Even later, they meet the Neon Knight of Malpraxis (who prefers to be called "Jim"). He joins Wander and Sylvia, but during a battle, he is hardly any help as he is busy recounting a boring fishing story. Later, he falls in love with Princess Veronicron. Wander and Sylvia leave him, but remember him fondly. Wander correctly answers the riddles of the Blarnian Bridge Troll. Wander and Sylvia cross the mountain pass, and avoid looking at a hippogriph. At the suggestion of the Lost and Found Guy, they make a pit stop at Bloyd's Diner for some blegg salad sandwiches. Wander then somehow has a meditation of self-discovery.
Some time later, Wander and Sylvia finally arrive at the mountain of the Intergalactic Guru, but find they have to climb a long staircase. When they get to the top at last, Wander asks the Intergalactic Guru, "Is this your sock?", but the Guru replies, "Nope." Sylvia is upset at this since Wander should have asked him whose sock it was, not if the sock belonged to the guru. When Wander talks about how long it would take to find who the sock belongs to, Sylvia claims that it is her sock after all. Wander is not convinced by this claim, since Sylvia does not wear socks, or shoes for that matter. When Sylvia attempts to put the sock on, Wander fights with her and they tumble down the long staircase. When the sock lands on Sylvia's nose, a slip of paper emerges from the sock. Wander looks at it and discovers that the return address was inside the sock the whole time.
On a rather dark and grimy planet, Wander asks the inhabitants how to get to 1313 Looming Terror Drive. An inhabitant opens his window and points forward to a rather evil-looking castle. Sylvia refuses to go up to the castle, since she's certain that they are going to die if they go up there. Sylvia is already planning an escape from the planet, but Wander is already heading up to the castle, so she follows him. She distracts one of the guards by throwing a rock. The guard runs in the direction of the rock. They run into the hall of the planet's ruler, Destructor. Wander is about to ask Destructor if the sock belongs to him, but Destructor instructs the guards to seize them.
Wander and Sylvia are tied to a chain-linked rope dangling over a huge cauldron of boiling oil. Wander asks the executioner if Destructor ever lost a sock. The executioner tells him Destructor lost one sock, but he bought a new pair. The executioner lowers the crank. Wander apologizes to Sylvia about dragging her on this quest only to meet their doom and says that Sylvia was right about it only being a dumb sock. Wander drops the sock into the cauldron, but Sylvia catches it with her tail before it goes into the liquid.
Sylvia is convinced that the sock actually matters to Wander, and does not want the quest to end in vain. She throws the sock to Destructor and asks if it belongs to him. Destructor is about to destroy them when a high-pitched voice says, "Stop!" Destructor asks who said that, and it turns out to be Destructor using the sock as a puppet. The sock tells Destructor to remember. In a flashback Destructor used to be gold and happy while having fun with his sock puppet, until his father takes the sock away from him, due to having to give up childish things if he wants to rule the kingdom. As a result, he grew angry, thus turning the entire kingdom dark and grimy like in the present, and imprisoned the residents and his own father.
Back in the present, Destructor turns gold and becomes happy that he is reunited with his sock. He thanks Wander and Sylvia for returning his sock puppet. He tells the guard to release them and all the prisoners and make them dukes, except for one prisoner, whom he tells to make an archduke. He forgives his father and the planet becomes bright and happy again, much to Wander and Sylvia's confusion.
As the sock bids farewell to the two, Wander says to Sylvia that he thought someone's foot would get cold, and she frowns, ending the episode.
Wander discovers a lost teddy bear in the road. Another epic quest of unfathomable difficulty is avoided when the owner claims the bear.
- Jack McBrayer as Wander
- April Winchell as Sylvia
- Fred Tatasciore as Lost and Found Guy, Destructor
- Keith Ferguson as Destructor's Father
- Craig McCracken as Desctructor's sock voice
- Kari Wahlgren as Princess Galactica, Princess Veronicon
- After Wander suspects something about the man claiming lost items, if examined closely while Sylvia explains to him about the Lost and Found, Wander can be seen with an eyebrow. Before she finishes speaking, the eyebrow disappears.
- When the man says "so named for its fierce grizzlock population", the captions list "grizzlock" as "grizzly".
- During the scene with the Guru, Wander's armband and missing sock leg, and Sylvia's loupe, tattoo and leg brace keep switching sides. Also in one scene when climbing up the mountain, Sylvia's loupe is gone, only to reappear in the next scene.
- After Destructor's father is freed, they are inside the castle, but when he goes to hug them, they are in the village.
- Tom Kenny is credited for the voice of Peepers despite him not appearing in this episode nor speaking in "The Void".
- When Sylvia grumbles, "Rassafrassin' crystal, rassafrassin' quest!", the captions do not change on the second sentence.
- It is unknown why Sylvia did not ask the Guru who the sock's owner was after Wander asked only if the sock was the Guru's. The Lost and Found man states that you may only ask the Guru one question, presumably meaning one question per person.
- This episode, so far, has the longest title in the series.
- The episode's title card is unusual, since "EPIC QUEST" appears first in all caps, while the rest of the title appears after it in lowercase.
- In the village square near the beginning, one of the creatures from the Theme Song can be seen walking around.
- The staff that Wander carries when he and Sylvia reach the Millon-quinquog-interquadratentillion Steps is the same one he was originally drawn with in Craig McCracken's concept art.
- Bloyd's Diner is most likely a nod to Lloyd's Diner in Framingham, Massachusetts.
- The episoce was originally known to be named "The Epic Quest".
- This is the first episode to use the new, shortened theme song on episode-purchasing services and Watch Disney XD / On Demand.
- Also, as of this episode, the credits are now 16 seconds instead of 30 seconds, since they scroll faster and the animatics are shortened.
- Craig McCracken (the creator of Wander Over Yonder) made a cameo in this episode as Desctructor's sock puppet voice.
- August 8, 2014 (Disney XD Brazil and Latin America)
- August 9, 2014 (Disney XD Spain)
- August 16, 2014 (Disney XD Canada and Poland)
- November 22, 2014 (Disney Channel Hungary)