When Wander disobeys Sylvia as usual, he discovers mysterious crystals which cause his personality to split up into multiple duplicates of himself. This causes him to slowly fade from existence, and it is up to Sylvia to round up the Wanders before her friend disappears forever.
The episode starts with Wander and Sylvia chasing a baby squirrel to get it back to its mother and siblings in a tree. Then the squirrel runs towards a mysterious crystal cave. Despite Sylvia's protests, Wander goes up to the cave, anyway, and is in awe of the crystals as each one shows his reflection, until he steps on to a platform and his personality splits into multiple Wanders.
Sylvia finally approaches the cave and notices Wander running away, until suddenly a stampede of Wander trample over her and begin to cover the planet. Sylvia, confused and worried, runs into the cave and sees a transparent, wide-eyed illusion of Wander. She then witnesses a Sleepy Wander fall into the illusion and appear in a crystal. The Intelligent Wander tells her that the indigenous crystals have broken his personality into fragments, and if not restored in time the original Wander will disappear forever.
Sylvia desperately tries to catch all 420 Wanders but with no success. After some encouragement from the Encouraging Wander and Cheerleader Wander, she decides to catch them using their traits as bait. So she catches all the Wanders and throws them back into the cave into the original Wander, but is confused as he is not restored and realizes she forgot someone. She turns around to face the Disobedient Wander who is taunting her. Sylvia refuses at first, thinking that Wander is better off without that part of him. But, she realizes that all of his personalities make up the real Wander, plus he will disappear if she doesn't do it. So she devises a trick to lure the Disobedient Wander into the cave and finally catches him.
Sylvia reluctantly puts him back into Wander, and he is seemingly restored and declares they need to stop Lord Hater and that he is perfect now. Sylvia, suspicious of this new behavior, remembers that the real Wander wants to befriend Lord Hater and realizes that one more Wander is missing. Wander tells her he's better off without it, but Sylvia tells Wander that every part of him is important and puts him back on the platform and looks for the last Wander. She turns a corner in the cave and finds a Young Wander, terrified and crouched in a corner. The Zen Wander tells her, "The helper seeks to help because he knows what it is to be helpless." Sylvia kindly helps Young Wander, causing him to smile. Sylvia puts him back into original Wander and all the Wanders in the crystals disappear and Wander, now officially restored, smiles and sheds a single tear. He tearfully thanks Sylvia, for that was his most important part.
Later, Wander and Sylvia push a big boulder into the entrance of the cave so as to ensure nobody else goes through the same experience again. Wander and Sylvia then leave the planet, off to their next adventure.
- "Wander Over Yonder End Title Theme" (instrumental)
- This is the second episode with multiple Wanders ("The Void").
- This marks the first time Wander is seen with bare feet.
- This is the second time someone is seen at a younger age, with the first being Destructor in "The Epic Quest of Unfathomable Difficulty!!!".
- The idea of this episode was first made by Dave Thomas' six-year-old son Charlie.