For several months there have been attacks from strange monsters that the ponies of Equestria have never seen before. On the day of the Summer Sun Celebration, a star falls from the sky and crash lands in the Everfree Forest, and produces a warrior that has the power of ridding the Kingdom of Equestria of the strange monsters...a tiny, round, and pink warrior named Kirby.

With the return of Nightmare Moon, Kirby ends up helping Twilight Sparkle search for the Elements of Harmony to stop her from keeping the night eternal.