Luna is asked by her father to bring important medicines to her aunt, who appears to live in a little village in the Crystal Mountains. Unfortunately, she lost her way in a snowstorm as she try to join the village and is supernaturally saved by a mare, who bring her to "Reef Castle", a surreal manor hidden in the shadow of a mountain. For the two months to come, she has to stay with the only three occupants of the castle, the gardener, the servant and the master, as her life become more and more strange.

(In this universe, Alicorns aren't know by the general population, who believe that the sun and moon move by themselves; but of course all will be explained later in the story. There will possibly be a bit of clop too.)