The first (and last) time the slimmest crescent moon fell on the night of the Summer Sun Celebration, something new was created. It waited for thousands of years, formless… Until now. When Tirek, the horror of the Underworld, was defeated, there was finally enough magic for this entity to take a physical form: New Moon, a unicorn filly with extraordinary mental powers. However, things don't go as planned, and New Moon is left with the memory of a typical Ponyville resident, and no memory of who she truly is.