When Gumball and Darwin investigate a missing classmate, they discover a far greater mystery…about Elmore. Gumball and Darwin start noticing small details around Elmore High that don't add up. They come to the conclusion that Molly has disappeared, even though nobody else remembers her ever having existed. Mr. Small confirms their suspicions and tells them that things are not always what they seem in Elmore. They set off on a quest to rescue Molly in an alternate dimension, and soon need rescuing themselves!