Stephen King's The Wind Through the Keyhole takes place between books four and five of the Dark Tower series. Similar in structure to book 4, Roland and his friends stop on their way to Calla Bryn Sturgis and Roland tells them two stories, which make up the vast majority of the book.
The first story is pulpy horror western. Shortly after the return from Mejis, young Roland and (the extraordinarily forgettable) young gunslinger Jamie must save a down on its luck wild west town from an apparent werewolf.
The second story is a fairy tale with just a touch of North Central Positronics. A boy named Tim must save himself and his mother from a wicked stepfather - - the cover of the book is an illustration of the adventure he goes on.
Both stories are wonderful, and Tim's story could easily become the foundation for an entire new series. Highly recommended. The cover price is an outrageous $27 for only 300 pages, but you can buy it for about half off at Amazon.