In an alternate universe, the twin nations of Equestria and the Crystal Empire have ruled side by side during a thousand year period of harmony. The Crystal Empire, ruled by Princess Radiant Hope and Princess Mi Amore Cadenza, has grown significantly since its early days as a single, if impressive, city. In Equestria, meanwhile, Princess Celestia and Princess Luna have shared a peaceful reign together since their defeat of Discord a millennium before. They even run a successful magic school together, and have two highly gifted personal protégés, Sunset Shimmer and Twilight Sparkle.

However, the peace cannot last forever. The Grand Equestria Pony Summit is approaching, and scores of ponies are arriving just to get a chance to see all four princesses together at once. In the shadows, a group of ponies has plans to awaken an old enemy long forgotten. Should they succeed, lives will be lost, bonds will be broken, and old wounds will be reopened.

Can the power of friendship win in a world where no one can be trusted? Not even yourself?