A retelling of the Lunar Rebellion. The cult of the waxing moon has opened a doorway so that the antithesis of harmony can reach the minds of ponies. Luna will use her old friend Cobalt as a head of the cult and overthrow her sister to sate her greed

A new pony arrives in Ponyville, unresponsive and frail. Twilight believes that something dark has followed him after reading his journal, but does not know what it is or why. Nightmares creep into their dreams, and start invading their waking lives.