If you've been following with the books I've read you know I got to the fourth book of The Dark Tower series, and before reading Wolves of Calla I was recommended to first read the book that King intended to tie in to the novel series way later on in 2012. King does a good job of making the book flow into the series. For Dark Tower fans particularly though it will be exciting to have a new book in the series exploring the mid-world that Roland resides in.
Summary: Roland, Susannah, Eddie, Jake, and Oy the billy-bumbler are on their way to the Outer Baronies, but a storm halts them in their path as they travel. As they are stormed in Roland tells a story within a story. He begins with one that accounts his early days as a gunslinger when he was sent by his father to find a shape-shifter than had been terrorizing the village. He meets Bill Streeter, the only boy in the village who has lived the attack of the shape-shifter and may be the only one who can identify him. To calm him he tells him the story of a boy named Tim from a popular childhood story his mom would tell him from a story time book.
