After annoying all of his friends, SpongeBob decides to pack up his belongings and leave Bikini Bottom forever. A bump on the head causes him to lose his memory, and he finds himself mayor of New Kelp City. When Sandy, Patrick, Mr. Krabs, and Squidward finally find him, it will be up to SpongeBob to either return to his old life with these "strangers," or remain in the city where he's considered a hero.