The Secret Princess!
Since their trip to Poni Island made them realise that their father, Mohn, is still alive, Lillie and Gladion return to the Aether Paradise and investigate their father's old office. When there, Lillie discovers her father's old Z-Ring and the Mythical Pokémon, Magearna. Lillie approaches Hala and asks if it's alright for her to use her father's Z-Ring, and so they have a battle to see if Lillie can master the Z-Moves. Will they find more information about their father's location?