They say Luna turned into Nightmare Moon soon after she and her sister had taken down the Tyrant King Sombra. What they don't know is that it was more than just a coincidence. He was once the pillar that held her up. She was too much for one to bare.
Twilight Sparkle traverses the Arctic with Sombra as she tries to learn about the mystery that was Starswirl the Bearded's life. But are these secrets what she thought they would be? And just who was Starswirl anyway? Sombra seems to know, but why?