A Very Special Holiday Episode: The Call of Wings by Agatha Christie

Most people know the apocryphal tale of Agatha's sister challenging
her to write a murder mystery, but years earlier--1912 or
thereabouts--her mother is supposed to have challenged her to write
as a way of entertaining herself while recovering from influenza.
Apparently this lead to an extended bout of neophyte creation that
included this rather spiritual yarn, which just may remind you of
another classic Christmastime story....