We had the category winners earlier in the month, and yesterday Frances Hardinge's The Lie Tree was announced Costa Book of the Year.
It's the first children's book to win in more than a decade, but the judges said "we all loved this dark, sprawling, fiercely clever novel that blends history and fantasy in a way that will grip readers of all ages".
It sounds very interesting indeed - as you'll see if you pop over to the author's website, and watch a short interview with her here.
Edited to add: a quote from this article by Philip Womack -
"The Lie Tree is a substantial text that is complex and intelligent: a lustrous, delicious romp about evolution and feminism, which contains a Hamlet-esque revenge plot. Crucially, [...] it comes from a place of wonder. Regardless of the age of the reader, our whole literary system is predicated on wonder, a fact that is often neglected [...]"