When the eccentric Uncle Grandpa takes his magical RV for a spin, things go hilariously wrong. He accidentally shifts the vehicle into the wrong gear and goes crashing straight through the boundaries between dimensions, tearing across the worlds of several beloved Cartoon Network shows. Along the way he unwittingly scoops up a ragtag band of heroes: Gumball, Clarence, Steven Universe, Mordecai and Rigby from Regular Show, and Finn and Jake from Adventure Time. The dimensional collision leaves chaos in its wake, spawning a menacing army of shard-born Mirror Clones scattered across the shattered realms. Now this unlikely team of cartoon champions must band together, each bringing their own quirky abilities to the fight, and battle their way through six worlds themed after their respective shows. Traveling from one universe to the next, they punch, smash, and blast through waves of enemies in a bid to set the dimensions right again.