Princess Twilight Sparkle should have known. She should have at least seen the deception. The result of her error led to Equestria falling into the combined forces of the detestable King Sombra and the changeling Queen Chrysalis. Both had been presumed defeated. A foolish presumption. Evil never dies easily. Now it is up to Twilight Sparkle, trapped with Discord in a cave, Applejack, Rarity, Rainbow Dash, Pinkie Pie, Fluttershy, Spike, and a few others to return Equestria back over to the rightful rulers as well as defeating evil.