Celestia is gone. No-one knows how, or why. But all Luna knows is that it was Celestia's wish for her to take the throne of Equestria by herself, and continue to rule in her absence.
But Luna refuses to accept that Celestia is gone. She feels like she will fail, and that her sister will not love her anymore. But all it takes is a voice in the wind for her doubt to disappear.

Once upon a time, in the land of Equestria, two royal sisters rules over the kingdom and created harmony for everyone. To do this, the elder raised the sun at dawn, an the younger brought out the moon at dusk.
One day, the elder realised how much her subjects relished and enjoyed her sister's night, but shunned and hid away from her light. Running out of ways to make them love her warmth and light again, she decides on one final resort, but at a great cost. Everything shall burn.