The Map decides to suddenly send the Mane 6, plus Spike, on an adventure that will enlighten them all about history that pre-dates their coming into this world. Along with the aid of a new, and mysterious friend.

But as they learn about the past before the past. An older, and far more dangerous enemy then any that has come before, will reveal itself.

(takes place after Twilight's Kingdom episode.)

(Highly inspired by LOTR and similar references)