MOTZKIN LIKED IT in Lisbon. He’d done the glamour postings. He’d done London. He’d done Paris and Brussels. He’d spent a nail-biting year in Cairo posing as a journalist from a newspaper in Ottawa. It was quiet in Lisbon these days, and that was fine with Motzkin. The odd surveillance job, a bit of liaison work. Just enough to keep him from going stir crazy. He had time for his books and his stamps and for long siestas with his girl in the Alfama.

He had just returned from her flat when the telephone on his desk rattled softly. Motzkin lifted the receiver and brought it cautiously to his ear. This was the time Ari Shamron usually chose to poke his head out of his foxhole and make life miserable for his katsas. But thankfully it wasn’t Shamron-just the guard down in the lobby. It seemed there was a visitor, a man who knew Motzkin’s name.

Motzkin rang off and punched up the lobby surveillance camera on his computer monitor. The station regularly fielded walk-ins of all shapes and sizes. Usually a quick once-over could determine whether the person should be seen or frog-marched to the gate.

As the image appeared on his screen, Motzkin murmured: “I’ll be damned.” Imagine, the living legend, walking into the embassy, looking like something the proverbial cat dragged in. Last Motzkin had heard, he was holed up in some English cottage with his paintings and his demons. “I’ll be damned,” he repeated as he clambered down the stairs. “Is it really you?”

IN the communications room, Motzkin established a secure link with Shamron’s office at King Saul Boulevard in Tel Aviv. Then he closed the soundproof door and watched Gabriel through the glass. It was an unpleasant conversation; that much Motzkin could tell. But then there were few people inside the Office who hadn’t crossed swords with the old man at one time or another, and the battles between Shamron and the great Gabriel Allon were the stuff of Office lore. Twenty minutes later, when Gabriel slammed down the telephone and stepped out of the room, his face was ashen.

“The old man is sending a report through in thirty minutes. I need a few things.”

Motzkin took Gabriel upstairs to the station and allowed him to shower and change into clean clothing. Then he arranged airline tickets and a car and gave him two thousand dollars from the petty-cash box.

By the time they returned to the communications room, the report was sliding off the secure fax machine. It had been compiled by Research Section at King Saul Boulevard and was based on information shared through standing agreements with British and French intelligence.

The subject was a man named Christopher Keller.

Gabriel scooped the pages from the tray, sat down at the table, and started to read.

BORNin London, the only son of two successful Harley Street physicians, Christopher Keller made it clear at an early age that he had no intention of following in the footsteps of his parents. Obsessed with history, especially military history, he wanted to become a soldier. His parents forbade him to enter the military, and he acceded to their wishes, at least for a time. He entered Cambridge and began reading history and Oriental languages. He was a brilliant student, but in his second year he grew restless and one night vanished without a trace. A few days later he surfaced at his father’s Kensington home, hair cut to the scalp, dressed in an olive-drab uniform. Keller had enlisted in the British Army.

After basic training, he joined his infantry regiment, but his intellect, physical prowess, and lone-wolf attitude quickly set him apart from his peers. Soon a recruiter from the Special Air Service came knocking. He had seen Keller’s file and spoken to his superiors. Keller was invited to the Regiment’s headquarters at Hereford to undergo the initial training course.

His performance was extraordinary. The instructors in the unarmed combat course wrote that they had never seen a man who possessed such an instinctual knack for the taking of human life. In the “killing house”-an infamous facility where recruits practice close-quarters combat, hostage rescue, and antiterrorist “room clearing” drills-Keller achieved the highest possible scores. On the final day of the course, he carried a fifty-five-pound rucksack and ten-pound assault rifle during a forty-mile march across the windswept moorland known as the Brecon Beacons, an endurance test that had left men dead. Keller completed the course thirty minutes faster than any man had ever done it before. He was accepted into the Regiment and assigned to a Sabre squadron specializing in mobile desert warfare.

Then the course of his career took an abrupt turn. Another man appeared on the scene, this time from military intelligence. He was looking for a unique brand of soldier capable of performing close observation and other special operations in Northern Ireland. He said he was impressed by Keller’s linguistic skills and his ability to improvise and think on his feet. Was Keller interested? That night he packed his kit and moved from Hereford to a secret base in the Scottish Highlands.

During his training Keller displayed a remarkable gift. For years, British security and intelligence forces had struggled with the myriad of accents in Northern Ireland. In Ulster, the opposing communities could identify each other by the sound of a voice. The accent of Catholic West Belfast is different from that of Protestant West Belfast; the accent of the Upper Falls Road is different from that of the Lower Falls. The way a man uttered a few simple phrases could mean the difference between life and an appalling death. Keller developed the ability to mimic the intonations perfectly. He could even shift accents at a moment’s notice-a Catholic from Armagh one minute, a Protestant from Belfast’s Shankill Road the next, then a Catholic from the Ballymurphy housing estates. He operated in Belfast for more than a year, tracking members of the IRA, picking up bits of useful gossip from the surrounding community. He worked alone, with almost no supervision from his case officer at military intelligence.

His assignment in Northern Ireland came to an abrupt end one night when he was kidnapped in West Belfast and driven to a remote farmhouse in County Armagh. There, he was accused of being a British spy. Keller knew the situation was hopeless, so he decided to fight his way out. By the time he left the farmhouse, four hardened terrorists from the Provisional Irish Republican Army were dead. Two had been virtually cut to pieces.

Keller returned to Hereford for a long rest. He took punishing hikes on the Brecon Beacons and trained new recruits in the art of silent killing. But it was clear to the Regiment’s commanders and psychologists that Belfast had changed Keller.

Then in August 1990, Saddam Hussein invaded Kuwait. Five months later, Keller and his unit were roaming the western desert of Iraq, searching out and destroying the Scud missile launchers that were raining terror on Tel Aviv. On the night of January 28, Keller and his team located a launcher in the desert one hundred miles northwest of Baghdad. He passed along the coordinates to his commanders in Saudi Arabia. Ninety minutes later, a formation of Coalition fighter-bombers streaked low over the desert, but in a disastrous case of friendly fire, they attacked the SAS squadron instead of the Scud site. British officials concluded that the entire unit was lost, though no conclusive remains were ever found.

What came next was essentially a theory-again based on intelligence reports. Some months after the disaster in the Iraqi desert, a new and highly professional killer was reported to be working in Europe. Police informants spoke of a man known only as “the Englishman.” None could offer more than the vaguest descriptions of him. To date, the mysterious assassin was a suspect in at least twenty unsolved murders. British intelligence suspected that Christopher Keller and the Englishman were the same man.

The file concluded with two photographs. The first was the one Gabriel had taken of the man entering the gallery in Paris. The second showed a group of men on a deserted moorland. One of the faces was circled. Gabriel spent a long time comparing the two pictures. Then he picked up the telephone and called Shamron in Tel Aviv. “I have the strangest sensation I’ve actually met this man before,” Gabriel told him. He had expected Shamron to be surprised by the remark. Instead, the old man told him to stay near the fax machine, and then he rang off.

IN1988, Gabriel Allon carried out one of the most celebrated operations in the history of Israeli intelligence: the assassination of the PLO’s second-in-command, Abu Jihad. He had conducted a long and dangerous surveillance operation on the Palestinian’s villa in Tunis, and he had trained the hit team at a mockup in the Negev desert. Then, one warm night in April, he led a team of Sayaret commandos into the house and shot Abu Jihad to death in front of his wife and children. Thinking about that night now, he could still see the look of pure hatred in their dark eyes.

Eighteen months after the assassination, a team of British intelligence and SAS officers involved in the fight against IRA terror came to Tel Aviv to study the tactics of the Israelis. Ari Shamron summoned Gabriel to the Academy and compelled him to deliver a luncheon lecture on the Tunis operation. One of the men attending the lecture was an SAS lieutenant.

The item that came across the fax machine was a photograph. It had been taken after the luncheon to commemorate the spirit of cooperation between the secret warriors of the two countries. Gabriel, eternally camera-shy, wore sunglasses and a sun hat to conceal his identity. The man next to him stared directly into the camera lens. Gabriel carefully examined the face.

It was Christopher Keller.