Why aren't there all the books in a series sometimes
Thank you for your great question! There are a few reasons we might not have all of a series. In some cases the series or author's popularity may have waned on older material, and we simply have to make room for new items coming in, so an old title or two in a series might go away.
However in your particular situation, I have good news. With The Straw King and other 'extra' novellas in the series, the author is following a new trend and first only making them available in an electronic format. We actually have some of these other e-novellas in the series available for download right now (Right here)!
But there's even better news! Many authors then later take these novellas and publish them all together in one print edition, and that now has happened to the Straw King. We just ordered the collection (Dorothy Must Die Stories, Vol 2), and you can place a hold on it here. Volume One, including prequel novellas, is also available.
That's probably more than you ever wanted to know, but if you have any further questions, please let us know.
Thanks again for asking!