The Mare in the Moon has returned, and the dark power that created Nightmare Moon is awakening again with the aid of a magical Moonstone. The two princesses and the Mane Six must use the Elements of Harmony to banish the darkness once and for all. Meanwhile, on Prehistoric Earth an alien artifact identical to the Moonstone falls into Predacon hands. What does this mean? And what will happen when a rift in space is opened between the two stones, pulling the Transformers into the strange, new world of Equestria?

(Note: It gets dark in places, but there is no explicit violence or gore.)