When Twilight accidentally catches the two Princesses arguing, she at first just passes it off as nothing. Luna is but two years removed from her imprisonment in the Moon, and she hasn't shown any signs of ever wanting to go back to being Nightmare Moon. Besides, Celestia doesn't seem to be worried.

However, Twilight is shocked to find that Luna officially breaks ties with Celestia, vowing to overthrow her "unjust leadership," and even more shocking is that some of her own friends are siding with Luna.....and therfore against Celestia and Twilight herself. War is looming over the once tranquil land, and the cities and villages across the land draw lines and pick sides, gearing up for the first pony on pony war since the very founding of Equestria.

Is harmony and friendship dead forever? Will, or can, anyone survive? And what will befall what was once the most peaceful nation in history?