The Defector by Daniel Silva

Another solid installment in the Gabriel Allon series, look forward to the next. PW: Six months after the dramatic conclusion of Moscow Rules, Gabriel has returned to the tan hills of Umbria to resume his honeymoon with his new wife, Chiara, and restore a seventeenth-century altarpiece for the Vatican. But his idyllic world is once again thrown into turmoil with shocking news from London. The defector and former Russian intelligence officer Grigori Bulganov, who saved Gabriel’s life in Moscow, has vanished without a trace. British intelligence is sure he was a double agent all along, but Gabriel knows better. He also knows he made a promise. In the days to come, Gabriel and his team of operatives will find themselves in a deadly duel of nerve and wits with one of the world's most ruthless men: the murderous Russian oligarch and arms dealer Ivan Kharkov. It will take him from a quiet mews in London, to the shores of Lake Como, to the glittering streets of Geneva and Zurich, and, finally, to a heart-stopping climax in the snowbound birch forests of Russia. Faced with the prospect of losing the one thing he holds most dear, Gabriel will be tested in ways he never imagined possible. And his life will never be the same.