Sweetie Belle just had the best winter vacation in the Crystal Empire. She got to meet her colleagues from International Magic University, spent a day with Flurry Heart, and have a blast with all the festivals. But all good things have to come to an end and it was time for Sweetie Belle to return home for the holidays. But then things took a wrong turn.

After missing a train, Sweetie Belle was left stranded in the middle of a winter wasteland, the nearest town miles away. Freezing, Sweetie Belle tries to find shelter or help. Only to be nearly killed by a yeti beast. Only through sheer luck did Sweetie Belle manage to escape by jumping into a small hole in the ground. This secret tunnel led to a lost cave in which a mysterious being resided. This creature is the custodian of a long, lost race.

After securing her a shelter, this custodian offered Sweetie Belle a deal into learning about the magic of his lost master from beyond the stars. Sweetie Belle is hesitant. Such magic would be interesting but it is being kept from her from this mysterious being. But as Sweetie Belle debates, a new threat is emerging. Something that might put all of Equestria in danger. Soon, Sweetie Belle will have to make a choice. And that choice might have a price she will have to pay.

Set in the same universe as Autumn Scarlet but not a direct sequel. So, you can read this one first if you like.
Happy First Day of Winter!