The Secret Princess!

Since their Poni Island experience made them realize that their father Mohn is still alive, Lillie and Gladion return to Aether Paradise and go through their father's papers, hoping to find some clues. Back at the family mansion, Lusamine shows them Mohn's old office, where Lillie discovers her father's old Z-Ring and the inoperative Mythical Pokémon Magearna. Lillie goes to Kahuna Hala and asks for permission to use her father's Z-Ring, and they have a battle to see if Lillie can master Z-Moves. Will Lillie and Gladion learn anything new about their father's whereabouts, and what is Magearna's connection to Mohn and Lillie?