"Twenty-five years after the epic battle between Pops and Anti-Pops, Mordecai, Rigby, and the rest of their friends return to the park for a reunion! Their crazy youth is nothing but a memory... or so Mordecai and Rigby think. It's not long before these two friends stumble across a secret fairy world, find themselves young again, and have their children stolen by Viceroy Alberich, the Fairy King. Now 25 years younger, Mordecai and Rigby must work...