An interesting and enjoyable modern thriller that walks on the edge between science and magic. The conceit of the book is that certain word patterns can short circuit decision making and force someone to obey a command. This knowledge is carefully guarded and selectively shared among adepts. The exact words needed to command someone depend on the target's personality type, so the adepts practice both hiding their own personality types and learning to observe others. The book covers the training and plotting of these adepts against each other, especially as a new uber-command-word is uncovered. There are lots of nice touches to the book. The writing is of a general high quality, and I very much liked the characters, the plotting, the action scenes, and a number of small and vivid details/ideas. The main bad guy in particular was a hoot. The ending turned out to be a bit trite, but the journey was enjoyable.
While I mostly liked the book, it never completely came together for me and made it into the territory of 4 or 4.5 stars. I think part of the reason is that I had issues with the world building given the central conceit. It's basically the same problems I had with _The Night Circus_. The first problem is that don't like these sorts of mind-mages as protagonists. Their whole schtick is enslaving people, so it is like having Southern plantation owners, or the _Deepness in the Sky_ slavers, or Aboleths as your protagonists. Now, you *could* do this and write a very dark book, but that should be a conscious choice. What doesn't work for me is when you make your protagonists all slavers, and then more or less ignore your choice. It makes the tone all wrong for me at several points in the book.
The second problem is that I can't see how a society of these people could reasonably develop. If anyone around you could enslave you by uttering a few words, I feel like you kind of have to kill/enslave them first, if for no other reason than to stop them from doing it to you. Encounters between mind-mages seem like they should be like encounters between people on _The Road_. At best, each mind-mage would have their own small empire of enslaved servitors, where at least a little stunted society could exist. Actually, come to think of it _A Deepness in the Sky_ did have this, and did put some actual thought in to how these masters could more-or-less safely interact. So, go Vinge?