In an alternate universe, Prince Sombra and Princess Twilight are the future rulers of Canterlot Kingdom. Prince Sombra has a gift. He can make black crystals! But when his powers injure his sister, his parents lock him up away from her.

After their parents pass, Coronation Day comes, naming Prince Sombra the new King. But when an accident causes his powers to slip, he puts a curse on the kingdom, and flees. Now, Princess Twilight is headed out to go find him. She is accompanied by a Crystal Pony/ Snowman named Cadence, an Earth Pony named Big Macintosh, and his dog, Winona.

But what she doesn't know is that King Sombra has not just put a curse on the kingdom, but himself.