We've talked about Seanan McGuire's work under her pen name of Mira Grant here on the site. As herself, McGuire writes my favorite urban fantasy series, the Toby Daye books. (Begin with Rosemary and Rue.) She has a gift for finding the heart of a story.
That gift is fully in evidence here in "Lost." "Lost" originally appeared in the 2009 anthology, Ravens in the Library, and was reprinted in the June 2012 issue of Lightspeed.