There are many graceful old buildings on the rue de Grenelle in Paris, entirely intact, but none house an elite counterterrorism unit of the DGSI called the Alpha Group, for no such unit exists. Also, one will search in vain for the headquarters of the Israeli secret intelligence service on King Saul Boulevard in Tel Aviv; it was moved long ago to a spot north of the city. The Liberty Crossing Intelligence Campus in McLean, Virginia—home of the National Counterterrorism Center and the Office of the Director of National Intelligence—was destroyed in a terrorist attack in The Black Widow but, fortunately, not in real life. Employees of the two agencies work day and night to keep the American homeland safe.

Gabriel Allon and his family do not reside at 16 Narkiss Street in Jerusalem, but occasionally they can be spotted at Focaccia or Mona, two of their favorite neighborhood restaurants. There are several art galleries in the centre ville of Saint-Tropez, some better than others, but none bear the name Olivia Watson. Nor will visitors to the St. James’s section of London find an Old Master art gallery owned by anyone named Julian Isherwood, Oliver Dimbleby, or Roddy Hutchinson. The paintings referenced in House of Spies were quite obviously used fictitiously. The author has no comment on the manner in which they were acquired. Nor does he wish to imply that the murderous ruler of Syria maintains an account at the esteemed Bank of Panama.

The title of part 3 of House of Spies was suggested by a line from The Sheltering Sky, Paul Bowles’s masterwork. The line also appears in the text of my novel, along with a portion of the subsequent sentence and one of Bowles’s part titles. In addition, I borrowed iconography from Bowles—and poetry from Sting, also an admirer of The Sheltering Sky—in my depiction of Natalie Mizrahi’s brief moonlit foray into the sand dunes of the Sahara. Obviously, Gabriel plundered F. Scott Fitzgerald’s The Great Gatsby and Tender Is the Night when devising his operation, and it was more elegant as a result. Fans of the film version of Dr. No will doubtless recognize where Christopher Keller found his inspiration when describing the stopping power of a Walther PPK pistol.

I completed the first draft of House of Spies, with its depiction of two ISIS terrorist attacks in London, one successful, one foiled, on March 15, 2017. At 2:40 p.m. on March 22, Khalid Masood, a fifty-two-year-old convert to Islam, turned onto Westminster Bridge in a rented Hyundai. While crossing the Thames River at speeds reaching seventy-six miles per hour, he mowed down several helpless pedestrians on the southern pavement and then crashed the car into a railing in Bridge Street, outside the Houses of Parliament. There he stabbed to death forty-eight-year-old police constable Keith Palmer before being shot by an armed officer from the Metropolitan Police Service’s close protection command. In all, the attack lasted eighty-two seconds. Six people died, including Masood, and more than fifty were wounded, some with catastrophic injuries.

The threat level at the time was “severe,” meaning an attack was “highly likely.” Four months earlier, however, Andrew Parker, director general of MI5, was even more blunt in his assessment. “There will be terrorist attacks in Britain,” he told the Guardian newspaper. “It is an enduring threat and it’s at least a generational challenge for us to deal with.” ISIS’s tactics differ from those of al-Qaeda. A suicide vest, a gun, a knife, an automobile, a truck: these are the weapons of the new jihadist terrorist. But ISIS has loftier ambitions. The group’s external operations division is feverishly attempting to build a bomb that can be smuggled onto a commercial airliner without detection. And there is ample evidence to suggest ISIS has been trying to acquire the ingredients for a radiological dispersion device, or “dirty bomb.”

With the caliphate of ISIS under siege from the United States and its coalition partners, the flow of foreign fighters from the West and other Middle Eastern countries has slowed to a trickle. Still, ISIS has proven adept at recruiting new members to its ranks. Oftentimes, they come with a criminal past. ISIS does not shun them. Quite the opposite: it is actively recruiting new members with criminal records, especially in Western Europe. “Sometimes people with the worst pasts create the best futures.” So read a social media posting issued by Rayat al-Tawheed, a group of ISIS fighters from London. The message was clear. ISIS is willing to employ criminals to fulfill its dream of building a worldwide Islamic caliphate.

The nexus between crime and radical Islam is one of the most disturbing emerging trends confronting U.S. and Western European counterterrorism officials. Take, for example, the case of Abdelhamid Abaaoud, the presumed operational mastermind of ISIS’s attack on Paris in November 2015. Born in Belgium and raised in the Molenbeek section of Brussels, he served terms in at least three prisons for assault and other crimes before joining ISIS. Salah Abdeslam, Abaaoud’s accomplice and childhood friend, was also a petty criminal; in fact, they were once arrested together for breaking into a parking garage. Ibrahim El Bakraoui, who detonated a suicide bomb inside Brussels Airport in March 2016, fired on police with a Kalashnikov assault rifle during a 2010 attempted robbery of a currency exchange bureau. His younger brother, Khalid, who detonated a suicide device at a Brussels metro station, had a long criminal past that included convictions for several carjackings, a bank robbery, kidnapping, and weapons charges.

Numerous ISIS operatives have come from the world of illicit drugs, and ISIS has been linked to drug smuggling in the eastern Mediterranean almost since its inception. But there is now evidence to suggest that the group, with its finances under strain, is involved in North Africa’s lucrative hashish trade. Not long after the fall of Muammar Gaddafi in Libya in 2011, Western European police noticed a sharp increase in the flow of hashish from Morocco, along with a change in the traditional smuggling route, with Libyan ports serving as the primary point of departure. Had ISIS, which had established a presence in post-Gaddafi Libya, somehow attached itself to the hashish trade? European police couldn’t say for certain. But they received a piece of welcome news in late 2016 when Moroccan authorities arrested Ziane Berhili, allegedly one of the world’s largest producers of hashish. Berhili was the owner of a large dessert company in Morocco. But according to Italian authorities, he made most of his money by smuggling an estimated four hundred metric tons of hashish into Europe each year. The street value of those drugs would be somewhere in the neighborhood of $4 billion.