It was a night like any other at Canterlot High...until someone steals a precious object from a display case by the principal's office. It was a ruby gemstone, once belonging to famous author A.K Yearling, when she once visited the school three years before.
Principal Celestia enlists the help of former school bully Sunset Shimmer and gem lover Rarity and their friends to help track the enemy-and it wasn't who they expected.