Sequel to Magic in the Stars...I would advise reading that first before venturing here.
For nearly four months, a young pegasus stallion has been living a life many have dreamed of, but he alone has experienced. Starfall has been at Canterlot, undertaking advanced astronomy studies under the Guardian of the Night, Princess Luna herself. But in these four months, both pegasus and alicorn have been hiding a secret from the world of Equestria...a relationship that delves much deeper than that of student and mentor.
With this relationship keeping Starfall in near-constant proximity to the Lunar Princess, he has been training under the Royal Guard, learning the skills needed to defend himself, and the Princesses, should the need ever arise. But Starfall is struggling in his training, while Luna is dealing with her own personal issues in the wake of the return of the mysterious, ancient Crystal Empire.
The couple decide to take a trip to the mysterious city in the middle of Equestria's desolate Frozen North, Starfall to see if Shining Armor can provide a new insight to his training, Luna to search for answers Canterlot and Ponyville have both failed to provide. Both wish to also treat it like a holiday, and perhaps take some time to indulge in simple, romantic pleasures that have been sorely lacking in their secretive lives so far.
But as they get settled in to the Crystal Empire, demons from both Starfall and Luna's past rear their heads. With their shared world spiraling out of control, and dark forced looming on the horizon, can their secret relationship possibly remain hidden? Can it even survive the coming storm? Can Equestria itself survive? Starfall's courage and very life have been pushed to the limit once already. This time, it might not be enough...