This novel, like the previous books in the Gabriel Allon series, could not have been written without the assistance of David Bull, who truly is among the finest art restorers in the world. I spoke to many intelligence officers, diplomats, ambassadors, and Bureau of Diplomatic Security agents while preparing this manuscript—men and women who, for obvious reasons, I cannot thank by name. Suffice it to say that because of them I know far more about embassy security procedures—and the way in which the United States would respond to an attack like the one portrayed in the novel—than I would ever put in a work of entertainment during a time of war. I would be remiss, however, if I did not extend a warm thanks to Margaret Tutwiler, the former undersecretary of state who was serving as the American ambassador to Morocco on September 11, 2001. Her descriptions of that day, some terrifying, others uproariously funny, provided me with a unique perspective of what it is like to be inside an American embassy in a time of crisis. I am honored to call her a friend, and grateful for her service.

The remarkable Bob Woodward generously shared with me his knowledge of the cooperation between the CIA and Egyptian security services. The eminent Washington orthopedist Dr. Benjamin Schaeffer taught me how to crudely treat a bullet wound in the field, while Dr. Andrew Pate, the renowned anesthesiologist of Charleston, South Carolina, explained the side effects of repeated ketamine injections and the symptoms of idiopathic paroxysmal ventricular tachycardia. Martha Rogers, a former federal prosecutor and now a much-in-demand Washington defense attorney, reviewed the case against the fictitious Sheikh Abdullah. Alex Clarke, my British editor, accompanied me on a fascinating journey through Finsbury Park and Walthamstow in the days after last summer’s London airline bomb plot, while Marie Louise Valeur Jaques and Lars Schmidt Møller gave me a tour of Copenhagen that I will never forget. A special thanks to the housepainter who verbally assaulted my wife and children on the Groenburgwal in Amsterdam. He unwittingly provided the inspiration for an opening chapter.

I interviewed many Islamists while serving as a correspondent for United Press International in Cairo in the late 1980s, but Journey of the Jihadist by Fawaz A. Gerges gave me additional insights into the minds of Egypt’s religious radicals, as did A Portrait of Egypt by Mary Anne Weaver. While Europe Slept by Bruce Bawer and Menace in Europe by Claire Berlinski helped sharpen my thoughts on the dilemma facing Europe today, especially the Netherlands, while Londonistan by Melanie Phillips gave me a deeper understanding of the crisis now confronting Great Britain. Ghost Plane by Stephen Grey contained many compelling personal accounts of those who have become ensnared, in some cases innocently, in the CIA program of “extraordinary rendition.” Over Here, Raymond Seitz’s memoir of his tenure as American ambassador to the Court of St. James’s, helped me create the world of Robert Halton.