On a trip to the zoo, Team Mystic encounters plenty of rare Pokémon. There are Abras, Mankeys, and Butterfree everywhere, not to mention a gazillion PokéStops. How lucky can a group of Pokémon GO players be? Then Gianna loses her lucky Pokémon-catching cap, and their fortunes take a turn for the worse. Now the kids have to stop looking for Pokémon and start looking for Gianna’s favorite cap. Team Mystic is on the case! But every clue the friends follow seems to lead a dead end, and soon they find their hopes of finding the cap fluttering away. Can an encounter with Butterfree help them find the lucky cap? Or has their luck run dry?