A TV announcer for Cartoon Network decides to take a day off and watch some of the company's television series. However, he finds that all these shows are facing utter destruction. Leading him to watch Ben Tennyson, who, seeing a newspaper article about the return of his arch-enemy, Vilgax, heads off to find him. Ben is then transported into another world. Ben then meets and fixes a corrupted Chowder. Then they find Vilgax and Mung Daal, which they defend Mung from villianous forces, while Vilagax escapes. The Ultramrix then detects a dimensional disturbance.
Chowder's dimension then disappears and the two are teleported to Rex Salazar's world, where they fight a corrupted Rex and Bobo Haha at Providence HQ. Rex and Bobo join Ben and Chowder to save Agent Six, Dr. Holiday and White Knight, rescuing Providence Agents along the way. Ceaser Salazar then teleports them to Abysus, where they find Van Kleiss and the Pack, and fight and defeat Van Kleiss and Biowulf. While the Pack is confused, Circe explains that after Ben and Rex defeated the Alpha Nanite, he was found by Vilgax as a remote control that allowed the user to journey into other worlds, whereat Vilgax created a Syndicate with other villians, including Van Kleiss. Kleiss then recovers and vanishes with Circe and the Pack, while Rex's world is destroyed.
The group then head to Ben's world in Bellwood, where they fight a corrupted Buttercup, while being taken to the Null Void. There, they find Vilgax, Van Kleiss and Biowulf(the Pack are there as well), who are then taken to Primus. There, they fight Ultimate Kevin Levin while the villians escape yet again. Max and Gwen are on Primus as well, and Kevin, Gwen and Max are stunned to see Chowder(although Kevin has met him before), Rex and Bobo. After explaining things to Max, he tells Ben to find Vilgax to stop him before all the worlds are destroyed, at which Ben's dimension is destroyed, but the heroes are saved by Dexter, who had built a dimensional capsule. They head to Stormalong Harbor, where they try to get Flapjack on board, by Stickybeard interrupts them, attacking Flapjack and are holding Gumball and Darwin Watterson captive on the Sweet Revenge.
While the others retreat, telling Flapjack they'll be back, Flapjack fends off the pirates (finding Captain Knuckles along the way). They fight Vilgax and a corrupted Numbah One and destroy The Sweet Revenge, rescuing Gumball and Darwin. They then fight Stickybeard inside Bubbie's mouth with Numbah one, and then are taken to the KND world after Stormalong Harbor is destroyed, along with the rest of Flapjack's dimension. At the KND Treehouse, they find Numbah Five, who joins the others to defend the Treehouse, also finding Numbahs 2, 3, and 4. They defeat the Tolietnator and Stickybeard's forces, and save the Treehouse.
Meanwhile, at Dexter's Laboratory, Father sneaks in and sabotages the capsule, sending Ben, Chowder, Buttercup, Rex and Bobo to Townsville(Powerpuff Girls' World), where Mojo Jojo is on a rapage in his giant robot. They find Blossom and Bubbles(who were corrupted before, but went back to normal after hitting the capsule's door). They travel to Professor Utonium's house, having rescuing him and Miss Bellum, then freeing the Mayor. they then battle one another to see who gets to enter Mojo Jojo's robot, at which the winner of that fight fights Mojo and saves Townsville. They then head to Foster's Home for Imanginary Friends (Mac and Bloo's dimension) and defeat a corrupted Mac and Bloo. They then rescue Cheese and the other Friends. Mr. Herriman, at first thinks that Ben and the others are Imanginary, but Frankie talks him out of it. They leave with Mac and Bloo just as the world is destroyed.
Menwhile, in the world of Adventure Time, Finn and Jake notice that Princess Bubblegum is missing. They found out that the Ice King has kidnapped her, so they venture to the Ice Kingdom, defeat the Ice King, and saves Bubblegum. Bubblegum says that Ice King has been mentioning a Syndicate to Gunther, and says something about a "space-like ghost", but before she can say anymore, she and the rest of Ooo is destroyed, and Finn and Jake somehow teleport to another world. They found Zak Saturday trapped by Argost and Munya. They find Argost and Munya who trapped Zak. They defeat Munya and frees Zak, who takes them to the other Saturdays, who are under attack. They, with the help of Doyle and Fiskerton, defeat the ongoing enemies and head to Camp Kidney after Zak's world is disappearing.
When arriving at Camp Kidney, they defeat a Dark Lazlo, whom only remembers his friends, Raj and Clam, being chased by " a human wirh a yellow glove", who turns out to be Van Kleiss. They head through the Kindey Lake, fighting enemies along the way. They reach the Jelly Ben Cabin, to find Van Kleiss trapping They battle Van Kleiss, save Raj and Clam, and escape to the world of Symbotic Titan, where they battle a corrupted Octus and Lance. Lance merely remember Ilana, who is under attack by General Modula. Once they rescue Ilana, Ben and the others appear in the capsule to take them to Dexter's Lab(with Flapjack, Knuckles, Numbah 1, Numbah 5, Gumball and Darwin, as well), only to find it on fire. They free Monkey, who was trapped. Due to the fact that Bobo and Lazlo are monkeys, they translate what Monkey was saying: Father was destroying the lab. They find Father and defeat him, as well as Aku.
They then head to Elmore High, where they find that the school is under attack. They rescue the students, save Ms.Simian, and defeat Vilgax and Munya. Penny then gives a kiss to Gumball, at which Chowder notices him blushing. They then head to Grim's world, where Billy and Mandy have been kidnapped by the villians. They defeat the corrupted Billy and Mandy, defeat a wave of zombies, and head into the Underworld. They defeat the Ice King, Mojo and Father once more once more, and the world vanishes. They then escape the dimension as it, to, is destroyed (Chowder just barely making it). They then take the capsule (the Announcer noticing how it's surprisingly roomier than it looks from the outside) to Samurai Jack's dimension. After defeating the corrupted warrior, Jack joins up with the heroes, but are attacked by Vilgax. After Vilgax's defeat, the now rather large group travels through Jack's world and defeats an army of Basket Robots.
Meanwhile, at the world of Megas XLR, Coop notices the deminsional mix-up after seeing something falling out of the sky, which turns out to be Cow and Chicken. Coop, Cow and Chicken fend off the oncoming monsters until the others arrive. They then jead to Courage's world, where they meet Courage, defeat Munya and Modula, and save Muriel. They then go Ed's world, where they save the Eds from the Klankers. In Ami and Yumi's world, they help the girls find their pets.
At Juniper Lee's world, they defeat a dark Juniper, who recalls Jasmine, Ray Ray, and Monroe being held hostage by Auntie Roon. The Heroes defeat Roon and save Juniper's family. They then head to the world of Regular Show, There, they meet Modrecai and Rigby, who notices the enemies and say that their boss, Benson, and their friends, Pops, Skips, Muscle MAn