Rainbow Dash isn't your ordinary pegasus. She has a secret ability that ponies thought only unicorns and alicorns could posses. Magic! Not magic like Twilight's though, Rainbow's is stronger. And dark magic.
King Sombra, the tyrant of Crystal Empire is back, only to be imprisoned by princesses and put through reformation with Twilight Sparkle as his teacher. Can somepony with heart as black as night be reformed? Twilight believes so.
Prince Shining Armor discovers a secret about Cadence's past that is almost as bizarre as why King Sombra lost the Crystal Empire because of Discord, Shining Armor hates his new inlaws & the crystal ponies are laughing hysterically at their new Princ
When Fluttershy goes into the Everfree to pick some berries for her date, she finds an unconscious pony near death. Normally, she would help them straight away but there is just one problem... It's King Sombra.