Sweetie Belle and Rarity have moved away from Ponyville, much to Sweetie's disgust. She hates the quiet and the snow, and she misses her friends. But all is not as it seems in the mountains, and a stranger is coming to visit...
Sweetie Belle has nightmares every night of a strange mare trying to hurt her. She didn't tell anypony, but she should have, because one night it gets worse.
When Sweetie Belle and the other Cutie Mark Crusaders explore the Castle of the Two Sisters, she comes across a strange artifact that sets into motion events that could change her life.