Rookie Wonderbolt, Rainbow Dash, awakens one day to find herself in an old abandoned castle with no memory of how she got there. The only thing she remembers is the storm.
The Wonderbolts are dead. Rainbow Dash has run away. Her friends are in disunity. When a dark stallion begins attacking, they need to band together against the storm and restore Harmony once more...but nopony seems to know where to start.