A purple Alicorn shows up one night and then vanishes into thin air. In a world of eternal night and mad gods most wouldn't think twice of the event.
Not Rainbow Dash. Rainbow Dash has met that Alicorn before.
The implications her appearance brings and the guilt that follows leaves Rainbow Dash with Questions weighing on her mind and a new purpose she never thought she'd have.
Luckily, even in the crushing pain of reality, she has friends.