When Twilight meets an alicorn princess named Autumn Breeze, she finds out that not only are her and her friends are in danger, but also all of Equestria-and everywhere else. Autumn tells her about Thunder Dust, the Princess of Destruction, who has taken Twilight's friends because they have the elements of harmony. Thunder plans on destroying all friendship and control from both Equestria and Celentoria, where Autumn is from, using Twilight's friends as her first test subjects. Can Twilight and Autumn save their home?