This book (6th in the Greenwing and Dart series) takes place during the leadup to Winterturn, which is obviously a Christmas analogue; it’s all snow and gifts and wild magic, driving back the dark, and getting ready for the turning of the year. It honestly felt quite a bit like Susan Cooper’s Dark is Rising. Goddard’s universe, which already involved old and new gods and religions, suddenly expands to include fairies, which took me a bit aback; however, it’s of a piece with the general theme of “weird stuff happens around Jemis Greenwing” so it’s easy to roll with.