The story begins in Asgard. Loki rides into Odin's throne room on his dragon. Odin asks what his business is, and Loki states he merely wishes for Odin to grant him permission to go to Earth and cause mischief and refuel his power. Odin grants him permission, and Loki rides to Earth to cause mischief. He stops by Elmore Junior High during the moment Gumball and Darwin watch Penny's unsuccessful cheering routine. Loki realizes he's spotted the perfect vessel from which he can cause mischief and takes possession of Gumball after the blue cat spots Leslie hugging Penny. Throughout the day, Loki causes mischief in Gumball's body. Later, Carrie and the gang perform the exorcism to remove Loki, and Loki pretends to be exorcised. Afterward, Loki takes the form of green energy, then takes on the form of sentient slime after Penny breaks the pepper circle, then continues his mischief. He then pretends to commit suicide by blowing up, then takes possession of Penny to continue his rampage. After his session, he leaves Penny's body, revealing his true form to the gang, then throws them away and leaves. He then flies back to Asgard, having succeeded in refueling his energy.