This is the second time I have picked up a novel only to realize part way through it was a second one in a series. The first time it happened it was with the Subtle Knife and the "His Dark Materials" series. It ultimately didn't effect my enjoyment of the novel then and it definitely didn't effect it this time either. After getting catching on who was who as I read along I really got into this book. I haven't read a lot of spy novels in the past but was able to jump right and it and get catch up. I am currently reading through the first novel in the series and it is just as good as this one. You could do what I did and start with the second book but I would starting with the first would be recommended. Great read overall!