To enjoy this book, you will need to accept the ridiculous concept of the Abelard Sanction. That is, the world's intelligence community got together (allies and enemies alike) and set up a system of safe houses where any operative could go and be protected from harm by any other operatives. Sure, it's hard to believe, but it is a key part of a very interesting story. It involves the familiar concept of teacher vs. student with some original twists thrown in. With each side trying to out-guess the other, you never know what is going to happen next.
Character development and dialog are not the strong points of this book. You do get a little background on how the characters became who they are, but the book is really all about action and intrigue. And it delivers on that.
... This is not great literature here, but it is a pretty good spy novel.