On a starry night of her making, Luna detects a disturbance in the dream world. When she moves to investigate, she encounters a horrific creature of terrible power and ill intent. This is a kind of nightmare she has never encountered before in her long years of dream walking, made all the more disturbing due to its ability to possess innocent ponies.

But there is something else intruding upon the dreams of Equestria: a small, spherical swordsman that seems to be dedicated to the total destruction of the formless shadows, heedless to any harm that may come to ponies caught in the crossfire.

It falls to Princess Luna, Princess of the Night and defender of dreams to discover the nature and purpose of the invading masses of darkness. As well as to see if the masked swordsman's intentions can be bent from pure destruction to preservation.