Yay! Only two books left on my C. J. Box catch-up project, Dark Sky (already on my Kindle) and Shadows Reel (coming out in March 2022). And this one is (of course) really good.
Joe Pickett is called in to investigate the shooting of the wife of a local judge. From Chapter One we know the bullet was fired from extreme long range, aimed at the judge himself. But he moved out of the way at the (literal) last second, and his wife was hit instead.
Unfortunately, the investigation is run by a new grandstanding sheriff, who ignores Joe's sage advice. The obvious suspects are those miscreants who bear a judge-grudge because of their harsh treatment. Joe suspects it's not that simple; he goes rogue, of course, and with his buddy Nate Romanowski, he makes slow and steady progress in tracking down the shooter.
In an independent plot thread, the Mexican drug cartel that Joe and Nate dealt with in the previous series book (Wolf Pack) is out for revenge; they send in one of their top professional killers to do the job, and things look pretty grim there for a while…
Also pretty grim: Missy, Joe's hellspawned mother-in-law, comes back into town. I thought Joe and Missy had a deal to prevent that, but that seems to have been memory-holed.
I think this is kind of unusual for Box: it's an actual mystery, and Joe is an actual detective. We only know what's going on pretty soon after Joe himself figures it out.