"The Wind in the Keyhole"... is a very odd story. It has three stories layered inside each other -- we have a person telling a story, in which he tells a story to someone else. 
 And while this new addition to the Dark Tower saga doesn't add a lot to the overall saga, it's a richly textured return to the "world that has moved on." Stephen King spends much of the book (when he's not merrily flipping through narratives) adding more dimensions to his raw, wild world, where a few brave individuals fight against the dark. 
 Roland, Eddie, Jake, Susannah and Oy take shelter in an abandoned house when a massive storm known as the "starkblast" blows in. To pass the time, Roland begins to tell his ka-tet a story from his youth, before his father's death and the fall of Gilead. 
 Shortly after his mother's death, his father sent Roland and another young gunslinger named Jamie to Debaria. A small mining town is being ravaged by a "skin-man" -- a shapeshifter who can appear as any kind of predator. With only one witness to the skin-man's rampages, Roland will have to play detective to figure out the killer's identity. 
 And during one of the quieter moments, he tells a young boy "The Wind Through the Keyhole." It's the story of a boy named Tim, whose father is unexpectedly killed, and whose mother remarries an old friend... who turns out to be an abusive drunk. Desperate to help his mother, he makes a disastrous trip to see an ageless black-cloaked man.... and when that goes horribly wrong, on a quest to find Maerlyn so he can make things right. 
 He ain't Catherynne Valente, but Stephen King does an impressive job stacking the stories inside each other like a matrushka doll. It's a little frustrating at times (you're left hanging for a LOOOOONG TIME about the skin-man's identity) but it's still very artfully imagined -- and he doesn't take the usual approach of just bundling together short stories. 
 This book also feels more intimate than the other Dark Tower novels, although the tax-collector in the story seems to be a pretty familiar villain. Hint: he always wear black. 
 As always, Mid-world is a place of dangerous creatures, blood'n'guts, Wild-Westy towns, a bit of steampunk technology and the feeling of a world that is slowly crumbling away into dust. But the story that Roland tells Young Bill also allows him to insert some scenes of haunting fantasy at the culmination of Tim's quest. 
 "The Wind Through the Keyhole: A Dark Tower Novel" doesn't add much to the overall ark of the Dark Tower books, but it adds more richness and depth to both Roland and Mid-world. A solid, enjoyable story... and story... and story.