Opaline Arcana has sowed dissent and anger across Equestria. With the nation divided, Princess Twilight Sparkle and her friends are struggling to contain the ambitious alicorn. If something isn't done soon, Twilight will have no choice but to store Equestria's magic into the Unity Crystals, putting all of ponykind at risk.

Before that, though, Twilight has an idea. There's a prisoner locked away in Tartarus that was forgotten by history. He might be just what they need to stop Opaline. However, letting him loose could spell disaster for Equestria.

It's a risk she has to take.