It's a normal day in the land of Ooo. In the Ice Kingdom, Ice King is walking his penguins when he happens upon a large block of ice. Inside it are three humanoid warriors, one wielding a spear, one wielding a whip, and one wearing gauntlets, and one human boy, who is wielding a shield. As Ice King looks at them in awe, a polar bear arrives on the scene and attacks Ice King and the penguins, and while doing so, accidentally breaks the ice containing the warriors, freeing them. The warriors are confused by their new surroundings. They then see the polar bear attacking the Ice King and his penguins and fend it off. Ice King thanks them, but flies back home. The warriors leave the Ice Kingdom and enter the Fire Kingdom. There, they happen upon the castle, unaware that Flame King has broken out of his prison, and intends on overthrowing Flame Princess. They knock on the door and ask for directions. Before they can get an answer, however, Flame King assassinates one of the guards, drawing the warriors' attention. Flame King sees the warriors and engages them in combat.

In the following battle however, which lasts about 20 minutes, Flame King is bested, and Flame Princess gives the warriors the Flame Kingdom's highest honors. The warriors then introduce themselves as "the Crystal Gems", the tall gauntlet bearing warrior is Garnet, the short whip wielding warrior is Amethyst, the spear wielding warrior is Pearl, and the human boy is Steven Universe. The Crystal Gems then leave the castle and explore the rest of Ooo. Eventually, they come across the Candy Kingdom, and one of the Gumball Guardians detects the Gems and, assuming they're evil, attacks them, prompting a counterattack from them. In the fight, they end up destroying the Gumball Guardian's head, and this catches Princess Bubblegum's attention. She comes down, and the Gems proclaim their innocence, explaining the Gumball Guardian made the first move. Instead of having the Gems banished, however, the princess allows them into the kingdom.

At the castle, Bubblegum asks the Gems why they're in the land of Ooo. Pearl says that the Gems were in the middle of a battle when the environment around them suddenly froze over. The next thing they knew, they were in a frozen wasteland (the Ice Kingdom) and found an old man (the Ice King) being attacked by a polar bear. Princess Bubblegum gives the Gems an offer, if they become her royal guards, then she'll forget what they did to the Gumball Guardian, and consider the damages to it paid for. The Gems accept the offer, realizing they're no longer in their home. Eight years later, something catches the Gems' eyes, a hand in the sky. The Gems recognize it, and head out to battle it.