Though daytime I do disappear
At night I'm always present, near
Your magic does naught
To keep me at bay
But all the while
I won't go away
Though try as you might
To ensure I'm gone
While we're in the night
You're never alone.

To Applejack, magic is a fickle thing; she's chosen to bear an Element of Harmony one day, and the next she's scratched by something while exploring a cave. What will she find of this lost magic and was it really lost or did somepony try to hide it?

Whatever it is, Applejack's going to find out.