Rarity sees herself in the market. It's definitely her, but it appears to be only an illusion because nopony else sees it, and they can walk through it with no trouble. She thinks it's just a trick, but when it comes back again inside the Castle of Friendship, Rarity starts getting concerned, she asks Twilight about it, but Twilight detects nothing with her wards. What might these apparitions want, and how can she get rid of them?