One year has passed since the marriage of Shining Armor and Princess Cadence, and things are quiet in Ponyville as usual, until Rainbow Dash and Rarity decide to take Twilight to Canterlot to celebrate her eighteenth birthday.

What they don't know is that every year, Twilight's dreams turn to memories warning her to stay away from Canterlot on that particular day. When she decides to ignore them this time, she risks her friends' lives, her magic, and the very freedom of Equestria.