With Harmony restored to Equestria, everypony needs to get back to work. Princess Luna is off to the Crystal Empire to guide the Crystal Ponies back into modern society, and Sunset Shimmer and Sterling Honor set off to retrieve the lost Elements of Harmony.

What starts out as a simple retrieval mission quickly grows complicated, and things don't seem to be making sense in the Crystal Empire either. As Sunset and Sterling travel across Equestria they start to unveil the seeds of a far darker plot than either expected - and a danger to Equestria that none were prepared to face.