Book excerpt: The #1 New York Times bestselling author of the Gabriel Allon series presents the second thriller featuring former CIA Agent Michael Osbourne, following The Mark of the Assassin. When the Good Friday peace accords are shattered with three savage acts of terrorism, Northern Ireland is blown back into the depths of conflict. And after his father-in-law is nominated to become the new American ambassador to London, retired CIA agent Michael Osbourne is drawn back into the game. He soon discovers that his father-in-law is marked for execution. And that he himself is once again in the crosshairs of a killer known only as October, one of the most merciless assassins the world has ever known...