Yellow Diamond, the queen of the Homeworld Gems, summons Peridot and sends her on a mission to Ooo, where pure energy has been discovered. As Peridot looks around, she comes across the Lich. They make a deal to harness the energy together, regardless of Yellow Diamond's orders. The two of them fuse, forming Perilich, and search for their first destination.
Dexter wakes up, ready to start the day. His father calls him down for breakfast, and finally tells the family the surprise he and Dexter's mother have been holding in until then -- after school, they are visiting his friend from college: Professor Utonium.
At Utonium's house party, Bubbles and Buttercup are playing tag. Blossom simply studies in her science textbook. Dexter notices her and instantly falls in love with her. He approaches Blossom and starts a conversation regarding school and science. But Blossom hears crashing noises in the lab, and goes inside to see what's going on. Dexter follows her.
Blossom and Dexter manage to stop Bubbles and Buttercup from wrecking Professor Utonium's lab. But Dee Dee, being so curious, presses a button and opens up a portal. Perilich comes out; after the group fights him (her? it? whatever), they separate back into the Lich and Peridot. Peridot says she has work to do in this dimension, and leaves. The Lich banishes Dexter, Dee Dee, Blossom, Bubbles, and Buttercup to the most remote dimension...
Characters Obtained: Dexter, Dee Dee, Blossom, Bubbles, and Buttercup.
Gumball and Darwin sit down to eat lunch. Darwin asks Gumball if he ever imagines a giant green hand crashing into the school building, and the latter is confused. They hear screaming from outside, and find mutant broccoli from The Powerpuff Girls invading the school. Gumball sees Dexter and co. lying dazed on the ground, and joins them.
The level consists of Dexter, Blossom, and Gumball looking for bits of cheese and a glass jar. The cheese will disintegrate the mutants, like it did when they were first fought in the PPG episode Beat Your Greens. Gumball melts the cheese and pours it into the jar, then puts it in the microwave. The result is a new variation of Kenneth, who will eat the mutant broccoli a la the TAWOG episode The Microwave. Kenneth holds the mutants off, while Dexter and co. realize that the giant green hand comes from the Homeworld Gem Warship; they go inside.
Characters obtained: Gumball and Darwin.
The group encounters Yellow Diamond, who has captured Bubbles. She plans to turn her into one of her Gem Warriors, but Buttercup frees her. Just as the warriors are about to destroy them, Finn the Human leaps in and joins the fight. Bubbles gets so nervous with the chaos that she lets out a super sonic scream that knocks out the Gem Warriors. Yellow Diamond pushes them out and flees.
Dexter builds an inter-dimensional traveler to help him, Dee Dee, and the Powerpuff Girls return safely home. But they'll have to go through several dimensions to find fuel sources. Gumball, Darwin, and Finn officially join them, alongside Penny.
Meanwhile, Mandark reports to Peridot regarding a strange being inside the Turner Portal, which is one month away from sucking up the Tooniverse. After the message ends, the Lich sets a course for the nearest dimension: Tokyo.
Characters Obtained: Finn and Penny.
Ami and Yumi have just finished their latest concert. As they are receiving congratulations, they find the Gangreen Gang from Powerpuff Girls picking on citizens. The girls fight them, but the KND Treehouse lands on the gang leader, Ace. The Kids Next Door step out and introduce themselves to Ami and Yumi.
They suddenly realize that zombies from the Billy & Mandy episode Night of the Living Grim are attacking as well. Ami, Yumi, and the Kids Next Door fight them off, and soon, Dexter's team appears.
The groups discuss what's going on, when the Gem Warship appears and captures the heroes...all except Gumball, Penny, and Finn, who are still in Tokyo, fighting off zombies.
Characters Obtained: Ami-Yumi and Numbuh One
Polyneux Middle School
It's a normal day for Robot Jones and his friends...until The Yogmans reveal that they have a tank-like machine from a friend. It starts to destroy the school until Mojo Jojo appears, holding the Principal in a cage. Trying to kill the gang, he sends an aray of moneky soliders at them. Suddenly, Shannon, Robot's crush, appears, and starts to fight Mojo. As that happens, Stickybear briefly appears and talks with Mojo, while Denny, one of the Yogman Twins, shows the gang a video made by Peridot. She explains that in exactly 30 days, the Tooniverse will be sucked up by the Turner Portal. Mojo then kicks the 4 into a portal, sending them to...
Characters Obtained: Robot Jones, Socks, Cubey, and Shannon.
Steven and the other Crystal Gems are hanging around, awhile after finding out Pearl's gem is cracked. Suddenly, Steven sees Robot Jones and the other 3 floating in the water. After saving them, the Gems and the kids exchange what's going on in each dimension when a cannonball is fired into their house.
It's revealed to be Stickybeard and his pirate crew. The 7 heroes (Pearl is resting) make it onto his pirate ship and start wrecking the place until Steven finds what's controlling the portals: a lever on the ship. He's about to turn it off when Pearl wakes up and sees what is happening. She thinks Steven is about to hurt himself, so she accidentally pushes the lever the wrong way, sending the entire ship and it's inhabitants to...
Characters Obtained: Steven, Garnet, and Amethyst.
It's a "normal" day in Endsville. Billy is being as dumb as ever, and Mandy wants to find Grim. They find Grim, trying to rest, when Mandy asks if he's seen any "green spirits." Suddenly, Billy points out the "the bald kid" is back, and points out the window to see Numbuh 1 and the rest of his crew...except for the 3 missing ones.
They talk for awhile until Robot and the Crystal Gems (except for Pearl) appears. They keep talking until Darwin predicts that a dragon will come along. As he says that, Aku, in the form of a dragon, appears and starts a fight with the gang. Samurai Jack appears along with Aku and starts to fight. The characters starts to fight as a team, and it leads Garnet and Amethyst to form Sugilite. After a long battle, Aku gets sucked into a portal back to the Gem Warship.
A Giant Robonoid appears, and a message from Peridot is played. It says that due to their victory, a prize is rewarded to them. That prize is Pearl's gem getting fixed. However, they notice the Turner Portal is starting to eat away at Dimsville. The group escapes in a ship crafted by Dexter and watch as this world was not able to escape the portal's wrath.
Characters Obtained: Billy, Mandy, Samurai Jack, Pearl, and Grim.
Gem Warship Cutscene
Professor Utonium and Dexter's parents arrive, being held hostage by Moxy, who's been hypnotized by Peridot to be her slave, The Lich, and Mandark. Peridot then reveals her plan: to get the Turner Portal to eat the Tooniverse, then rebuild it and become the empress. However, as time went by, Peridot noticed an orange throbbing circle in the portal, dubbed "The Heart." As Peridot is explaining what the adults will do as prisoners, a transmission comes in from an unknown source. Once translated, the transmission says that something will happen in 29 days. Peridot squeals in joy after finding a new revelation about "The Heart," and informs Moxy to take the adults to get turned into Crystal Soldiers so they don't rebel. As they leave the control room, Peridot smiles, not knowing what the last day will hold...
Characters Obtained: NONE.
The alarm in Dexter's ship goes off; it is being dragged into a tractor beam! Mandark uses it to lift Dexter out of the ship and drag him into Huber, which has been taken over. Dexter is brought to Peridot's office; the latter explains that she needs his brain matter to open up the Turner Portal. She also states that several buildings from other worlds have been appearing in Huber due to the predestination paradox caused in Dexter's Laboratory: Ego Trip. Peridot commands Utonium to take Dexter to the brain-sucking machine.
Mandark tells Moxy to pull the lever, but... he refuses. He says that he was only pretending to be brainwashed so he could gain access to the Gem Warship, and releases Dexter. Peridot sends some robots to stop them, but they are defeated. She fuses with the Lich again, forming Perilich. Peridot, being the mind and intelligence, tries to destroy Dexter, but she accidentally breaks the control panel. "The Heart" is released, and it reveals itself as Virus. He forces a fusion on Perilich, forming Terror. Mandy breaks in and tries to stop him, but is seemingly eaten by him. Moxy tells Dexter to find the portal levers, and takes the Yogmans with him to the ship.
Yumi attempts to dodge falling debris from other dimensions as she attempts to save Dexter with the ship. At the same time,Finn, Gumball, and Penny make it back from Tokyo, shaking off zombie limbs. Meanwhile, Dexter finds the levers, and almost pulls them all until Mandy -- who has actually fused with Terror and now calls herself Infinity -- smacks him away. She explains that she is now powerful enough to take over the entire Tooniverse, and tries to eliminate Dexter. She forces him to watch Blossom's peril, but he leaps out and pulls the last lever, forcing Infinity to break apart and Virus and Peridot to be sucked into the Turner Portal... along with Dexter himself.
Dexter and Peridot wake up, seemingly in the real world. A boy named Kyle finds them and sends them through a plastic tube back into the Tooniverse. Peridot apologizes for what she has done, and tells Dexter that the Lich has a Plan B to bring back Virus. Dexter, in return, agrees to let Peridot into his team -- once they're ready. Peridot returns to Homeworld for the time being, and Dexter reunites with Blossom and the rest of Team Legacy. Dexter and Blossom share a kiss, and the team prepares to put an end to Plan B...
Meanwhile, a team of heroes from another universe made it to Homeworld, and somehow arrested Yellow Diamond for "encouraging interdimensional travel." As such, she was taken to Interdimensional Jail and kept there. However, a mysterious visitor walks in and breaks open Yellow Diamond's cell, telling her "she's free." The camera pans around, and reveals the face of Vilgax, and a grin appears on his face.
Characters Obtained: Moxy, Peridot, The Yogman Twins, Finn, Gumball, and Penny