Princess Luna became Nightmare Moon one thousand years ago. That same night, she tried to overthrow her sister and was banished to the moon. When that happened, the largest community of thestrals watched.
With dissent growing among the normal ponies against those of the Night, Celestia tries to protect as many as she can. Riots break out. Vandalism, discrimination, and racism become commonplace. Thestrals are no longer safe on the streets.
Enter Constellation Nightmane. After witnessing the Celestia-Luna battle, she knows that she needs to find a way out. A way to prove that Luna was the only one who betrayed Equestria. Because if she doesn’t, a lot of innocent ponies - mares and stallions, fillies and colts, ponies and thestrals - are going to die in a brewing civil war.