I'm finding Wolves of the Calla a tough slog. I am enjoying it, but it's long. The main narrative gets sidetracked by lengthy flashbacks and it seems to suffer for it. While the flashbacks are interesting (and important plotwise), they interrupt the flow of the main plot. And one character has decided to not even finish his flashback, at least not until a more dramatically convenient moment. Still, King has set up an interesting situation here: a small village where most pregnantcies result in twins, but once a generation raiders (wearing wolf masks) come and take away one child from each set of twins, returning them a month or so later after they have been made into drooling idiots. "Roont" as the townfolk say.
Needless to say, Roland and company have rolled into town just before the next attack by the wolves.
How will it end? Who can say. Only Stephen King (and the millions of people who have the read the book before me) know for sure.