Stephen King is always a great story-teller! This book is no different. This is not the typical horror/slasher stereotype of a tale that might come to mind when you hear the author's name. This is one of his "other" books. There is plenty of evil, in a book about imprisoned children. There are innocents suffering, but at the same time, this book seems to be Stephen King having a moment of optimism in the face of darkness. I see two big themes here:

1. It is possible for victims to take back power from abusers by working together.
2. If you could shape the course of the world in ways that you see as beneficial or moral, but at the cost of committing cruelty upon innocents, would you?

Some reviewers have ranted about a handful of sentences in the novel where a character makes an anti-Trump comment. If you are so unable to handle an opposing idea that 5 or 6 sentences in an otherwise excellent novel will make you stop reading or boycott an author, then you have a very sad lack of tolerance, character, and intellect. People who take this path allow a knee-jerk reaction cut themselves off from seeing how Mr. King is making digs at both extreme ends of the political spectrum. Light spoiler:
2b, if you like, is this: Some of the actions taken by those wielding great power in this book might please the deranged absolute left end of the political spectrum, such as planning to murder a strident anti-gay-rights individual, for example. Even though this character is predicted to potentially damage human society on a great scale through his future actions, should he be murdered for the greater good? Should innocents be abused and suffer in order to effect his murder for the greater good? In this book, Mr. King answers "no"!

This is a book with conspiracy, psychic powers, and other entertaining elements, but it is ultimately about the idea that committing wrongs in the name of right should not be done. Mr. King seems to be reminding us that people, groups, and nations who want to stand for the greater good should take care that they do not use the tools of evil to pursue that good.

Also, it's a terrific yarn! Read this book!