When Daring Do's adventures come to a close in Equestria, and A.K Yearling stops the story she is confronted by Twilight and Rainbow Dash. They ask her to continue the story even if Yearling cannot continue them herself.
Twilight steps back in time to see what Sombra had in store for Equestria and his treatment of the Crystal Ponies. The story is set about 4 months after the Crystal Empire returned.