This is classic Stephen King, and this is why I read almost everything he writes. (I haven't read Gerald's Game or the Dark Tower series.)
A decent police officer and a politically ambitious DA, a horrific crime, a popular teacher and coach, seemingly overwhelming evidence - but things aren't what they seem. Eventually the detective agency from the Mr. Mercedes trilogy gets pulled in.
I'm not going to try to summarize beyond that; other GR reviewers are much better than I am at summarizing without spoiling.
As always, the characters are real. The good ones have a bit of heroism mixed in with a lot of human flaws. The bad ones have resentments, self-pity, and anger that can be manipulated to make them even worse. We spend most of our time with the good ones, which is what makes it possible for me to enjoy reading a book with such terrible things in it.
And the plot is a page-turner. I read half of it Thursday night and got to about fifty pages from the end on Friday; finished Saturday morning. It's satisfying and wise.
I noticed a couple of places where a pop culture reference is explained, in contrast to earlier King where references are dropped in and readers are expected to pick them up without help. I wonder if it's because pop culture is more fragmented now - we don't all see the same tv shows and movies - or because King's older now, so his references are drawn from a bigger pool of time that younger readers might not be familiar with - or if it's just a new editor with different preferences.