Tirek has escaped, commanding a dark force from his lair Midnight Castle, formerly located in the Summer Lands. Under his control are the Princesses Celestia and Serenity, the forgotten Princess of the Final Rest. Tirek's power is bolstered by magic from both Tartarus and the Summer Lands, as he gathers more power from the citizens of Equestria.

But all is not lost. While Princess Luna and Princess Cadance combat Tirek on the front lines, Princess Twilight Sparkle and her friends will journey through the darkest, deepest hell to save Celestia and stop Tirek's rise to power.