For the first six years of its existence, the Alpha Group was one of official France’s most closely held secrets, and its agents operated with impunity. That changed in the aftermath of ISIS’s attack on Washington, when press reports in America revealed that Rousseau had been wounded in the truck bombing of the National Counterterrorism Center in suburban Northern Virginia. Subsequent reports, mainly in the French media, went on to detail some of the Alpha Group’s more unsavory methods. Operations were compromised, assets identified. The interior minister and the chief of the DGSI responded by categorically denying that there was any such unit called the Alpha Group. But it was too late; the damage was done. Quietly, they urged Rousseau to forsake his anonymous headquarters on the rue de Grenelle and move his operation behind the walls of the DGSI’s headquarters in Levallois-Perret. Rousseau, however, refused to budge. He had never been fond of the Paris suburbs. Nor could his agent-runners carry out their duties properly if they were seen entering and leaving a walled compound bearing a sign that read ministère de l’intérieur.

And so, despite the elevated threat, Paul Rousseau and the Alpha Group continued to wage their quiet war on the forces of radical Islam from an elegant nineteenth-century building in the exclusive seventh arrondissement. A discreet brass plaque proclaimed that the building housed something called the International Society for French Literature, a particularly Rousseauian touch. Inside, however, all subterfuge ended. The technical support staff occupied the basement; the watchers, the ground floor. On the second floor was the Alpha Group’s overflowing Registry—Rousseau preferred old-fashioned paper dossiers to digital files—and the third and fourth floors were the preserve of the agent-runners. Most came and went through the heavy black gate on the rue de Grenelle, either on foot or by car. Others entered through a secret passageway linking the building and the dowdy little antique shop next door, which was owned by an elderly Frenchman who had served in a secret capacity during the war in Algeria. Rousseau was the only member of the Alpha Group who had been allowed to read the shopkeeper’s appalling file.

The fifth floor was somber and shadowed and quiet, save for the Chopin that occasionally drifted through Rousseau’s open door. Madame Treville, his long-suffering secretary, occupied an orderly desk in the anteroom, and at the opposite end of a narrow hall was the office of Rousseau’s ambitious young deputy, Christian Bouchard. It was an article of faith within the French security establishment that Bouchard would assume control of the Alpha Group if and when Rousseau ever decided to retire. He had tried that once before, after the death of his beloved Colette. The book he hoped to write, a multivolume biography of Proust, was but a pile of handwritten notes. He was now resigned to the fact that the fight against radical Islamic terrorism would be his life’s work. It was not a fight France could lose. Rousseau believed the very survival of the Republic was at stake.

In Gabriel Allon, he had found a willing if unlikely partner. Their alliance had been formed in the wake of Saladin’s Paris debut, the deadly bombing of the Isaac Weinberg Center for the Study of Anti-Semitism in France. Saladin had not chosen the target lightly; he had known of Gabriel’s secret ties to the woman who ran it. So, too, had Paul Rousseau, and together he and Gabriel had placed an agent of penetration in Saladin’s court. The operation had failed to prevent the attack on Washington, but it had all but ended decades of animosity and mistrust between the Office and the intelligence services of France. A welcome consequence of the new relationship was that Gabriel was now free to travel in France without fear of arrest and prosecution. His litany of sins on French soil, the killings, the collateral damage, had been officially forgiven. He was as legitimate as a career spy could possibly be.

The Alpha Group’s stringent new security measures required Gabriel to shed his motorcade and protection detail near the Eiffel Tower and to walk the remainder of the way alone. Usually, he entered the building through the gate on the rue de Grenelle, but at Rousseau’s request he came through the passage in the antique shop instead. Rousseau was waiting for him upstairs on the fifth floor, in the glass-walled, soundproof conference room. He wore a crumpled tweed jacket that Gabriel had seen many times before and, as usual, was smoking a pipe in violation of French laws banning the use of tobacco in the workplace. Gabriel was a devout nonsmoker. Still, there was something about Rousseau’s private rebellion he found reassuring.

He produced a photograph from his attaché case and slid it across the tabletop. Rousseau glanced at the face of the subject and then looked up sharply.

“Nouredine Zakaria?”

“You know him?”

“By reputation only.” Rousseau held up the photograph. “Where did you get this?”

“It’s not important.”

“Oh, but it is.”

“It comes from the British,” conceded Gabriel.

“Which branch?”

“MI6.”

“And why is MI6 suddenly interested in Nouredine Zakaria?”

“Because Nouredine is the one who supplied the Kalashnikovs for the attack in London. Nouredine is the one they call the Scorpion.”

There is no worse feeling for a professional spy than to be told something by an officer from another service that he should have already known himself. Paul Rousseau endured this indignity while slowly reloading his pipe.

“How much do you know about him?” asked Gabriel.