So the one I really like is the Alex Dryden series, which starts with Red to Black: http://www.amazon.com/Red-Black-Alex-Dryden-ebook/dp/B002JXB8CK/ref=sr_1_1?ie=UTF8&qid=1420587722&sr=8-1&keywords=alex+dryden.
It's a pretty classic KGB/MI6 spy intrigue series, written by a former journalist. If you're interested in modern Russia and it's roots in the KGB, they're great books.
And then if you've not read them, John Le Carre is the best.