Starlight Glimmer has been defeated, driven out of her village and into exile. In the aftermath of this, things are beginning to settle down in Equestria, and a new age of peace seems incipient. Fluttershy overcomes her fear of flying, a new pony arrives in Ponyville, and Twilight Sparkle continues to rule from her crystal castle.

To the west, over the rolling waves of the Luna Ocean, lies an isle inhabited by gargoyles. The northerners and southerners of that isle have been engaged in incessant conflict for many centuries, and have been deadlocked for just as long. Both sides have become weary, effete from the fighting. Under these conditions, a young gargoyle is sent east to Equestria on a mission of subterfuge, wherein his loyalties will be tested.