After defeating the Necromancer, Trixie is settling into her role as the new Element of Magic. It's a difficult adjustment for her, made harder by the fact that she doesn't trust any of her new friends. After all, just a few weeks ago those very same ponies were trying to kill her. Have they really changed? How can she possibly trust anypony ever again?

Trixie's life takes a turn for the worse when Celestia decides it's time to right an old wrong. All Celestia needs in order to open the Vault of Shadows is a sacrifice – and the princess has not forgotten Trixie's role in the death of Twilight Sparkle. Would it really be so wrong to offer Trixie? After all, Trixie should never have become the Element of Magic in the first place – and it's only natural for the little ponies to sacrifice for the greater ones. Right?

Join Trixie and Celestia on what proves to be one of the most terrible days of Trixie's life. By the time Luna raises the moon that night, somepony will fall – and Equestria will be changed forever.