So the big news here is that Lee Child (real name James Grant) has taken on a co-author for this book: Andrew Child (real name Andrew Grant, James' brother). And apparently the next book too, Better Off Dead, out in October, but available for pre-order at Amazon.
I'm sure the explanation is out there somewhere. I'm not that interested in finding out. The relevant question is: are there any noticeble changes to the tried-and-true formula?
Nothing major I could detect. Maybe Reacher is a little more verbal in his exchanges with friends and foes. Especially foes: Reacher is given to explaining to his opponents exactly why they should just give up instead of pushing Reacher into beating the snot of them. I'm not sure that would work well in a real-life situation. Why would a bad guy patiently wait for Reacher to finish his speech?
Anyway, Reacher (yet again) is just wandering around when he notices trouble a'brewing for an apparent innocent victim, Rusty Rutherford, who's being set up for a kidnapping by a team of four agents. They are, of course, no match for Reacher. After the rescue, Rusty seems clueless about why anyone would want to snatch him. He was, until recently, the IT guy for the local town government. Despite his best efforts, the town fell victim to a nasty ransomware hack. Rusty was fired and vilified. Still, kidnapping seems a little extreme.
Of course, Reacher suggests that Rusty simply leave town. That turns out to not be in the cards. So Reacher sticks around, investigating the hack, the kidnappers, and other mysterious goings on. And (as usual) there's a lot of violence, chicanery, and conspiracy. And (dude) even I picked up on the symbolism of the double-sided portrait at the end of the book. It's pretty heavy-handed.