The Defector by Daniel Silva

In Moscow Rules, Gabriel Allon life was saved by Grigori Bulganov. Grigori is now living in London under the protection of the British. He is kidnapped by a Russian millionaire, and Gabriel must go back into Russia to save his life. It's a interesting tale with breathtaking plot turns. It may be too violence for some people, but I liked it. It might be helpful to Moscow Rules first. I have read all of his books. I sometimes wonder why I like Gabriel Allon, but I do like him. PatM