Really three and a half. More detailed review to come after reading previous books in the series. Not that this doesn't work as a stand-alone, but there might be some things that would be easier to understand if one reads previous installments.Very realistic spy novel, particularly in comparison to likes of Bond and Bourne series. On the other hand, this realism does not necessarily work in its favour. POV is third person limited, with switches. This means use of spy and Oxford slang, and there is no glossary. One of blank pages at the end could have been spared. Switches worked, since narrators are obviously unreliable. Another thing that this realism brings us is very slow pacing, both in storytelling and action, which might annoy those looking forward to stereotypical spy thrillers. There are also a lot of names and contemporary references. This is not a book to be taken lightly.