Tenebrae Moonfallen is the Crown Prince of the ancient Bicorn race that existed 35k years ago before the modern-day Equestria two years after the coronation of Twilight Sparkle. Due to unknown circumstances during the last battle against a terrible enemy, he finds himself thawed out of ice into the modern world. And must acclimate to his new reality after knowing nothing but war. Where during his travels to find out what happened to his people and how he alone survived he learns that the great enemy is once again returning, but the modern world is too weak to resist such a threat.