The ponies of Equestria prepare for their first Friendship Festival, overseen by Princess Twilight Sparkle in Canterlot. The festivities are interrupted by an invasion of monsters commanded by the broken-horned unicorn Tempest Shadow, who uses magical obsidianorbs to petrify Twilight's fellow princesses. Twilight's group travel to the desert city of Klugetown in search of the aforementioned "hippos". A feline con artist named Capper offers to escort the group, secretly intending to sell them to settle a debt; however, he develops a genuine friendship with them. During a lunch break, the airship's birdlike Captain Celaeno and her crew reluctantly allow the group passage, revealing themselves to be former pirates that have been forced into the Storm King's service. Rainbow Dash persuades the pirates to defy orders and take the group to the hippogriffs' kingdom on Mount Aris. Abandoned by her friends over her actions, Twilight is abducted by Tempest and brought to the Storm King in Canterlot to have her magic absorbed; en route, Tempest gains Twilight's sympathy when she divulges how she lost her horn in a monster attack as a filly, which caused her own friends to shun her for her dangerously unstable magic. The Friendship Festival resumes, and the ponies celebrate with all of the allies Twilight's group have made on their adventure. Tempest is disheartened by her still broken horn until she is convinced by Twilight to join the party by producing a firework display with her magic, happily accepting the group's friendship.