Alex Dryden's 'Red to Black' is a detailed account of the origin of his Anna Resnikov series, narrated by the then KGB officer as she begins the relationship with a male British spy that sets it all in motion. Can enemy spies fall in love? That seems to be the question over the first 2/3 of the book, and when finally answered things move quickly.
The plot is fairly complex. Finn, the British spy, has been in place in Moscow for an extended period. The Russians successfully use a beautiful KGB agent, Anna, to get close to him to find out what or who he's working with.... not the classic 'honey trap', but nearly so. They develop a relationship, Anna dutifully reports back details to her superiors, but she's not giving them everything. In the meantime, Finn discovers a huge Putin plot against the West, but his superiors think he's gone off the rails. He 'retires' as a spy, but opts to free-lance his investigations using an assortment of characters from his past. Will Anna help, or burn him? You need to read Red to Black to find out. It's worth it.
By the way, although first published in 2008, the Putin-related passages and descriptions of how Russia began to devolve from a potentially democratic country to an authoritarian regime that's almost a criminal enterprise on a grand scale couldn't be any more timely. Although it's fiction, the author has done his homework.
I've unfortunately read the series in reverse order. They've all been decent and this is the best of the lot. The writing is fine but the dialogue, as I've found through the series, is uneven, though that may be related to the diverse nationalities of the characters involved. Descriptions of tradecraft seem real, which is always a bonus in espionage novels, and the characters were fleshed out very well. It's an exciting beginning to the series and explains a lot- would've been better for me to start here!