It's finally summer, and Ruby can't wait to play with her new friend, Zelda. Then she learns that Zelda is going on vacation with her family, while Ruby is stuck at home. Ruby's sister Iris reminds her of the Enchanted Realm and encourages her to go on an adventure. But Ruby has seen most of the magical land. She's explored the Fairy Forest, the Fire Mountains, and the Diamond Desert. She's made friends with unicorns and dragons. What else is there to discover? There are unicorns behind Magic Moon Stable, but no one knows they exist except Iris and Ruby. As Unicorn Guardians, the two girls must protect the unicorns to keep them safe from the outside world.