I t was Professor Solomon Rosner who sounded the first alarm, though his name would never be linked to the affair except in the secure rooms of a drab office building in downtown Tel Aviv. Gabriel Allon, the legendary but wayward son of Israeli intelligence, would later observe that Rosner was the first asset in the annals of Office history to have proven more useful to them dead than alive. Those who overheard the remark found it uncharacteristically callous but in keeping with the bleak mood that by then had settled over them all.

The backdrop for Rosner’s demise was not Israel, where violent death occurs all too frequently, but the normally tranquil quarter of Amsterdam known as the Old Side. The date was the first Friday in December, and the weather was more suited to early spring than the last days of autumn. It was a day to engage in what the Dutch so fondly refer to as gezelligheid , the pursuit of small pleasures: an aimless stroll through the flower stalls of the Bloemenmarkt, a lager or two in a good bar in the Rembrandtplein, or, for those so inclined, a bit of fine cannabis in the brown coffeehouses of the Haarlemmerstraat. Leave the fretting and the fighting to the hated Americans, stately old Amsterdam murmured that golden late-autumn afternoon. Today we give thanks for having been born blameless and Dutch.

Solomon Rosner did not share the sentiments of his countrymen, but then he seldom did. Though he earned a living as a professor of sociology at the University of Amsterdam, it was Rosner’s Center for European Security Studies that occupied the lion’s share of his time. His legion of detractors saw evidence of deception in the name, for Rosner served not only as the center’s director but was its only scholar in residence. Despite those obvious shortcomings, the center had managed to produce a steady stream of authoritative reports and articles detailing the threat posed to the Netherlands by the rise of militant Islam within its borders. Rosner’s last book, The Islamic Conquest of the West , had argued that Holland was now under a sustained and systematic assault by jihadist Islam. The goal of this assault, he maintained, was to colonize the Netherlands and turn it into a majority Muslim state, where, in the not-too-distant future, Islamic law, or sharia , would reign supreme. The terrorists and the colonizers were two sides of the same coin, he warned, and unless the government took immediate and drastic action, everything the freethinking Dutch held dear would soon be swept away.

The Dutch literary press had been predictably appalled. Hysteria, said one reviewer. Racist claptrap, said another. More than one took pains to note that the views expressed in the book were all the more odious given the fact that Rosner’s grandparents had been rounded up with a hundred thousand other Dutch Jews and sent off to the gas chambers at Auschwitz. All agreed that what the situation required was not hateful rhetoric like Rosner’s but tolerance and dialogue. Rosner stood steadfast in the face of the withering criticism, adopting what one commentator described as the posture of a man with his finger wedged firmly in the dike. Tolerance and dialogue by all means, Rosner responded, but not capitulation. “We Dutch need to put down our Heinekens and hash pipes and wake up,” he snapped during an interview on Dutch television. “Otherwise, we’re going to lose our country.”

The book and surrounding controversy had made Rosner the most vilified and, in some quarters, celebrated man in the country. It had also placed him squarely in the sights of Holland ’s homegrown Islamic extremists. Jihadist websites, which Rosner monitored more closely than even the Dutch police, burned with sacred rage over the book, and more than one forecast his imminent execution. An imam in the neighborhood known as the Oud West instructed his flock that “Rosner the Jew must be dealt with harshly” and pleaded for a martyr to step forward and do the job. The feckless Dutch interior minister responded by proposing that Rosner go into hiding, an idea Rosner vigorously refused. He then supplied the minister with a list of ten radicals he regarded as potential assassins. The minister accepted the list without question, for he knew that Rosner’s sources inside Holland ’s extremist fringe were in most cases far better than those of the Dutch security services.

At noon on that Friday in December, Rosner was hunched over his computer in the second-floor office of his canal house at Groenburgwal 2A. The house, like Rosner himself, was stubby and wide, and tilted forward at a precarious angle, which some of the neighbors saw as fitting, given the political views of its occupant. If it had one serious drawback it was its location, for it stood not fifty yards from the bell tower of the Zuiderkirk church. The bells tolled mercilessly each day, beginning at the stroke of noon and ending forty-five minutes later. Rosner, sensitive to interruptions and unwanted noise, had been waging a personal jihad against them for years. Classical music, white-noise machines, soundproof headphones-all had proven useless in the face of the onslaught. Sometimes he wondered why they were rung at all. The old church had long ago been turned into a government housing office, a fact that Rosner, a man of considerable faith, saw as a fitting symbol of the Dutch morass. Confronted by an enemy of infinite religious zeal, the secular Dutch had turned their churches into bureaus of the welfare state. A church without faithful , thought Rosner, in a city without God .

At ten minutes past twelve he heard a faint knock and looked up to find Sophie Vanderhaus leaning against the doorjamb with a batch of files clutched to her breast. A former student of Rosner’s, she had come to work for him after completing a graduate degree on the impact of the Holocaust on postwar Dutch society. She was part secretary and research assistant, part nursemaid and surrogate daughter. She kept his office in order and typed the final drafts of all his reports and articles. She was the minder of his impossible schedule and tended to his appalling personal finances. She even saw to his laundry and made certain he remembered to eat. Earlier that morning she had informed him that she was planning to spend a week in Saint-Maarten over the New Year. Rosner, upon hearing the news, had fallen into a profound depression.

“You have an interview with De Telegraaf in an hour,” she said. “Maybe you should have something to eat and focus your thoughts.”

“Are you suggesting my thoughts lack focus, Sophie?”

“I’m suggesting nothing of the sort. It’s just that you’ve been working on that article since five-thirty this morning. You need something more than coffee in your stomach.”

“It’s not that dreadful reporter who called me a Nazi last year?”

“Do you really think I’d let her near you again?” She entered the office and started straightening his desk. “After the interview with De Telegraaf , you go to the NOS studios for an appearance on Radio One. It’s a call-in program, so it’s sure to be lively. Do try not to make any more enemies, Professor Rosner. It’s getting harder and harder to keep track of them all.”

“I’ll try to behave myself, but I’m afraid my forbearance is now gone forever.”

She peered into his coffee cup and pulled a sour face. “Why do you insist on putting out your cigarettes in your coffee?”

“My ashtray was full.”

“Try emptying it from time to time.” She poured the contents of the ashtray into his rubbish bin and removed the plastic liner. “And don’t forget you have the forum this evening at the university.”

Rosner frowned. He was not looking forward to the forum. One of the other panelists was the leader of the European Muslim Association, a group that campaigned openly for the imposition of sharia in Europe and the destruction of the State of Israel. It promised to be a deeply unpleasant evening.

“I’m afraid I’m coming down with a sudden case of leprosy,” he said.

“They’ll insist that you come anyway. You’re the star of the show.”

He stood and stretched his back. “I think I’ll go to Café de Doelen for a coffee and something to eat. Why don’t you have the reporter from De Telegraaf meet me there?”

“Do you really think that’s wise, Professor?”

It was common knowledge in Amsterdam that the famous café on the Staalstraat was his favorite haunt. And Rosner was hardly inconspicuous. Indeed, with his shock of white hair and rumpled tweed wardrobe, he was one of the most recognizable figures in Holland. The geniuses in the Dutch police had once suggested he utilize some crude disguise while in public, an idea Rosner had likened to putting a hat and a false mustache on a hippopotamus and calling it a Dutchman.

“I haven’t been to the Doelen in months.”

“That doesn’t mean it’s any safer.”

“I can’t live my life as a prisoner forever, Sophie.” He gestured toward the window. “Especially on a day like today. Wait until the last possible minute before you tell the reporter from De Telegraaf where I am. That will give me a jump on the jihadists.”

“That isn’t funny, Professor.” She could see there was no talking him out of it. She handed him his mobile phone. “At least take this so you can call me in an emergency.”

Rosner slipped the phone into his pocket and headed downstairs. In the entry hall he pulled on his coat and trademark silk scarf and stepped outside. To his left rose the spire of the Zuiderkirk; to his right, fifty yards along a narrow canal lined with small craft, stood a wooden double drawbridge. The Groenburgwal was a quiet street for the Old Side: no bars or cafés, only a single small hotel that never seemed to have more than a handful of guests. Directly opposite Rosner’s house was the street’s only eyesore, a modern tenement block with a lavender-and-lime pastel exterior. A trio of housepainters dressed in smudged white coveralls was squatting outside the building in a patch of sunlight.

Rosner glanced at the three faces, committing each to memory, before setting off in the direction of the drawbridge. When a sudden gust of wind stirred the bare tree limbs along the embankment, he paused for a moment to bind his scarf more tightly around his neck and watch a plump Vermeer cloud drift slowly overhead. It was then that he noticed one of the painters walking parallel to him along the opposite side of the canal. Short dark hair, a high flat forehead, a heavy brow over small eyes: Rosner, connoisseur of immigrant faces, judged him to be a Moroccan from the Rif Mountains. They arrived at the drawbridge simultaneously. Rosner paused again, this time to light a cigarette he did not want, and watched with relief as the man turned to the left. When he disappeared round the next corner, Rosner headed in the opposite direction toward the Doelen.