I waited to read this short until after I had read [b:Shadow and Bone|10194157|Shadow and Bone (The Grisha, #1)|Leigh Bardugo|https://d.gr-assets.com/books/1339533695s/10194157.jpg|15093325], because I didn't want any spoilers, and I figured that I'd appreciate the story more after having read the first book, anyway.
Turns out it didn't really matter.
The Witch of Duva is a fairy tale set in the world of Shadow and Bone. Otherwise, the two stories have nothing to do with each other. They don't involve the same characters, or the same plot as the main series.
It was just an incredibly dark and depressing story within the world of the story, a cautionary tale that reads partially like Little Red Riding Hood, and partially like Hansel and Gretel, with just a touch of cannibalism thrown in, for good measure.
And I absolutely adored the short for that.