Princess Cadance is one of the most notale members of the royal family, being a powerful unicorn and the Headmaster of Canterlot's school of magic, not to mention being the one who personally trained Rainbow Dash in magic. So naturally Rainbow is ecstatic to be invited to her mentor's wedding, and her friends get to come along and help to! But while Rainbow is blinded by her idol worship, the others can't help but notice that something feels....off. The Groom is acting weirdly, Cadance is getting on their nerves, and they can't help but feel a little paranoid....like something's....watching. And waiting....