On February 21, 1973, a Libyan passenger plane, Libyan Airlines Flight 114, flying from Benghazi to Cairo, entered the airspace over the Sinai peninsula. The Sinai had been under Israel’s control since the Six-Day War in 1967, when Israel inflicted heavy losses on the Egyptian military and occupied the entire peninsula. Israeli jets scrambled to intercept the plane, making contact just after 2 p.m. The fighter pilots gave the universal signal ordering the Libyan plane to follow them. Their plan was to have the Libyan plane land at the air base in Rephidim, in the middle of the Sinai Desert.

At first, it seemed that the Libyan pilot was following. But as they closed in on the air base, the plane suddenly veered west, back toward the Suez Canal. The fighter pilots reported its unusual behavior and the fact that all the plane’s window shades were shut, making it impossible to see into the aircraft. The airliner was now heading west for the Suez Canal area covered by the Egyptian surface-to-air missile umbrella, which was off-limits to commercial traffic ― yet despite this, the surface-to-air missiles didn’t open fire. The whole Sinai had been a no-fly zone for civilian aircraft since Israel had captured it in 1967.

Add to this the fact that there had been explicit warnings about terrorists trying to blow up an airliner over Tel Aviv or another Israeli target, including the nuclear facility in Dimona, and the decision by the Israeli Air Force commander to request permission to shoot down the aircraft is not surprising. The chief of staff of the Israeli Defense Force, who had not slept the previous night because of an operation against Palestinian terrorists in Tripoli, Lebanon, was now awakened, and he promptly approved the request. A few minutes later, the smoking remains of the aircraft were strewn across the desert floor. Of the 113 passengers on board, less than 10 survived. One of the dead was Salah Bousseir, the former foreign minister of Libya.

Later on, it would emerge that the airplane’s communication system had failed. The pilot, who had strayed off course, at first thought the fighter jets were Egyptian and the airfield was Cairo International Airport. When he realized his mistake, he panicked and decided to make a break for it. Worried about the terror warnings and finding themselves under intense time pressure, the Israelis made a tragic mistake.

Bettmann/Getty Images An Israeli soldier stands guard over the charred wreckage of the Libyan Airlines 727 here. The plane was downed by Isreali jets over Sinai on Feb. 21, 1973. 92 persons were killed.

The Libyan leader, Col. Muammar Gaddafi, could not ignore what he and his citizens viewed as an unprovoked Israeli attack on a defenseless Libyan civilian aircraft. His first phone call was to Anwar Sadat, the president of Egypt, to talk about retaliation. Gaddafi’s proposals included attacking the Israeli port city of Haifa with Libyan bombers. Sadat, however, was concerned about ruining his plans for a surprise attack on Israel (Egypt would begin what became known as the Yom Kippur War less than eight months later) and urged restraint, though he could not say why.

But Gaddafi was not a man to whom restraint came easily. He was frustrated, and his people wanted blood. The public outcry reached its peak during the funerals of the victims, when crowds swarmed the Egyptian consulate in Benghazi, enraged at Sadat’s failure to protect the plane and his weak response to the crime.

Gaddafi decided to act without Egypt’s cooperation. On April 17, he summoned the captain of an Egyptian submarine stationed in Libya, functioning as part of the Libyan navy according to a military pact Gaddafi had signed with Cairo. The Libyan leader ordered the captain to sail east into the Mediterranean and to torpedo the famed British cruise liner Queen Elizabeth 2, which was on its way to Ashdod carrying dignitaries to Israel for the country’s 25th Independence Day celebrations. The captain asked for the order in writing, which Gaddafi supplied. After a full day undersea, the vessel surfaced and the captain radioed his commander in the Egyptian navy, reporting on his mission. The report quickly reached Sadat, who responded by ordering the captain immediately to head back to port in Alexandria. Soon after the QE2 had left Israel and was back out at sea, Sadat informed Gaddafi that the commander had failed to locate the British ship.

Wood via Getty Images The QE2 and tugs heading to Southampton, England.

Gaddafi didn’t buy it. The downing of the plane, coupled with his inability to retaliate, had fostered in the dictator a deep sense of impotence and frustration ― and he spiraled into a severe depression, even a personal crisis. He eventually traveled to Egypt and met with Sadat. During and after the visit, Libyan pressure on Egypt to unify their countries intensified; there was a mass march from Tripoli and other Libyan cities toward the Egyptian border. Egyptian pleas to stop the march were to no avail. In the end, the Egyptian army had to physically block about 40,000 Libyans trying to cross the border, with roadblocks and even freshly laid land mines.

In response, Gaddafi denounced Egypt and called for a popular revolution to root out the corruption and bureaucracy of Sadat’s regime. Sadat, who wanted to focus on nothing other than preparing for war against Israel, capitulated. On August 29, 1973, after a lengthy negotiation, the two nations announced that on September 1 ― the anniversary of the Libyan revolution ― they would sign documents to begin the process of unification. This was enough to calm the choppy waters of Egyptian-Libyan relations for the time being. But it did little to sate Gaddafi’s thirst for revenge.

Gaddafi spiraled into a severe depression, even a personal crisis.

In the often bizarre world of Middle Eastern politics, the Egyptian president’s greatest fear was that a serious Libyan retaliation against Israel would trigger a new Israeli-Arab war, ruining any element of surprise Egypt may have had in its own plans to attack. In his contacts with Gaddafi, Sadat repeatedly emphasized that any Libyan action had to be fully coordinated with Egypt, both in planning and in carrying it out. Reluctantly, Gaddafi agreed.

The man Sadat appointed to handle the matter from the Egyptian end was his emissary for Libyan affairs, Ashraf Marwan.

Maher Attar/Sygma/Corbis Gamal Abdel Nasser with his wife, his two daughters and their husbands. Ashraf Marwan stands next to Mona on the far right.

Mohammed Ashraf Abu al-Wafa Marwan, known simply as Ashraf Marwan, was the son-in-law of Sadat’s predecessor, Gamal Abdel Nasser ― one of the greatest Arab leaders in history. Marwan had married Nasser’s younger daughter, Mona, in 1966. He was ambitious, intelligent, born into a good family and handsome.

Nasser, however, didn’t trust Marwan. He ordered his chief of staff to investigate his daughter’s suitor while she and Marwan were dating, and the report was not flattering. It emphasized Marwan’s ambitiousness and his love for the high life, while doubting the sincerity of his feelings for Mona. But Mona refused to listen to her father’s concerns. She had made up her mind, and in the end, the greatest leader of the Arab world since Saladin was bested by his even more stubborn daughter.

At the wedding, not a word was mentioned about Nasser’s dissatisfaction with his daughter’s choice, even though the president was far from alone in his suspicions. One of Marwan’s friends recalled, years later, that his “marriage to Mona did not surprise anyone who knew him, and testified to his lofty ambitions.”

The greatest leader of the Arab world since Saladin was bested by his even more stubborn daughter.

Soon enough, Marwan’s marriage to Mona dramatically improved his status and brought him closer to the main centers of power in Egypt. He was soon transferred to work in the president’s office.

Marwan probably viewed the transfer as a step up, but he began to feel neglected by Nasser. The transfer was a sign of the president’s fragile faith in his son-in-law: he wanted to keep him close. Fully aware of that mistrust, Marwan failed to develop any significant relationship with him. Instead of mitigating the sense of distance and hesitation coming from Nasser, time had only made things worse. People who overheard exchanges between the two recall a young Marwan standing tense before his father-in-law, sometimes even quaking in his presence, stammering when he had to speak with him directly.

AP Nasser shakes hands with Marwan at the wedding.

His salary, meanwhile, was a pittance. The couple’s income was reasonable for a middle-class family, but it didn’t match their expectations for a better life. What was more, Cairo in the years after the defeat in the 1967 Six-Day War was not the hopping town it had once been, with a much greater focus on the growing conflict with Israel, including a military buildup that would allow Egypt to restore what had been lost (namely, honor and the Sinai Peninsula). Whether it was because he really wanted to go back to school or just to get out from under the eyes of his father-in-law, Marwan decided to put in a request to study abroad. Without a doubt, life outside Egypt looked more promising. In 1968, the Marwans relocated to London, where he was to undertake a master’s degree program in chemistry. Nasser gave his approval.

Marwan continued working in the president’s office during his studies in London. Despite a financial dispute with his father-in-law that almost ended with Nasser forcing the couple to divorce, it seems reasonable to conclude that Nasser eventually considered him the right man for certain sensitive tasks. He recognized Marwan’s specific talents, talents that could advance Nasser’s interests. Symbolically, Marwan embodied the personal will of the president. At the same time, he apparently had good access to senior figures of the military; they saw him as reliable and, in some cases, even one of them.

On the face of things, he was the archetypal Egyptian patriot.

This, however, was not enough for Ashraf Marwan.

In the summer of 1970, he was just 26 years old, a chemical engineer and an officer in the Egyptian army. He had successfully tied himself to the center of power, dining at the table of the greatest leader in the Arab world. On the face of things, he was the archetypal Egyptian patriot.

In truth, however, he was about to undertake the single greatest act of treason in his country’s history. Precisely why he chose to risk his life and career in order to help his country’s most despised enemy, in the midst of a conflict that daily spilled the blood of his country’s best youths, is a difficult question to answer.

STR/Getty Images Egyptian billionaire Ashraf Marwan on his wedding day with his bride Mona Abdel Nasser, daughter of late Egyptian president Gamal Abdel Nasser.

Marwan began his path to the Mossad, Israel’s intelligence agency, in one of those iconic red phone booths that used to mark London. Finding the address and phone number of the embassy did not require high-level espionage skills. They were in the phone book. When the switchboard operator answered, Marwan asked to speak with someone from the intelligence agency.

The operator knew the protocol. This wasn’t the first time she had fielded a phone call from someone with an Arab accent asking to speak with the embassy’s intelligence officer or a defense official. The procedures were clear. She transferred the call to the office of the IDF military attaché.

The attaché picked up the phone and responded politely. Marwan identified himself by name and asked to speak with the embassy’s intelligence officer. Like the switchboard operator, the attaché followed protocol. The name meant nothing to him, and Nasser’s son-in-law did not elaborate. The attaché took the slip of paper where he’d written down Marwan’s name and details and put it in the outbox on his desk. There it remained. The IDF attaché in London was not, at that moment, on especially good terms with the Mossad’s local representatives.

He was about to undertake the single greatest act of treason in his country’s history.

About five months after his initial contact, late in 1970, Marwan returned to London and decided to try again. But between his first attempt and the second, a major development had taken place: His father-in-law died after suffering a major heart attack. Nasser’s death had a huge impact on the course of Egypt’s history as well as that of the Arab world and of the Arab-Israeli conflict. It also brought changes in Marwan’s life. But what didn’t change was his determination to work for the Mossad.

Again, Marwan called the embassy and asked to speak with the intelligence officer, only this time he left a number where he could be reached. Like his predecessor, the officer, Maj. Gen. Shmuel Eyal, had troubled relations with the local Mossad officials, and he also failed to pass Marwan’s message along.

Express/Archive Photos/Getty Images Millions of people crowded Cairo's streets to witness Nasser's funeral procession in Cairo on Oct. 1, 1970.

It is hard to imagine what history would have looked like had fate not intervened. In mid-December, two senior Mossad officials arrived in London on unrelated business. Soon after arriving in London, they met up with Eyal and the local Mossad station chief, and the four agreed to drive together to Heathrow Airport. In the car, Eyal mentioned the Arab fellow who had been calling for a few days to offer his services, but who refused to come to the embassy in person. When they asked his name, Eyal said that he called himself Ashraf Marwan.

The three Mossad officials all looked at one another. They knew the name well.

Marwan had been in the Mossad’s sights for some time. His closeness to Nasser and access to materials that passed through his office would make Marwan a source of extreme value ― but until now, these same factors also made it hard to believe that he would ever work for the Mossad. What Eyal had said almost in passing, however, completely changed the picture.

Why did he chose to risk his life and career in order to help his country’s most despised enemy, in the midst of a conflict that daily spilled the blood of his country’s best youths?

The fear that Marwan would leave London without successfully making contact now set the pace of events. With no idea how much time they had to work with, the Mossad officials would have to improvise, bending the rules regarding meetings with agents.

They stopped the car, and the Mossad station chief got out and headed back to the embassy. It was not long before the telephone at the number Marwan had left was ringing. He was told that a meeting would be arranged in the lobby of a major hotel in central London. If everything went as planned, Marwan and his handler would talk in the lobby for a few minutes and then head up to a room that had been reserved on one of the upper floors, where they could speak openly.

A man named Dubi (his last name remains an official secret), the London station’s number-two official, was selected to meet Marwan. In his mid-thirties, a native Israeli whose grandparents had arrived in Palestine from Europe at the turn of the century, Dubi looked European but spoke fluent Arabic. This was an important consideration for the simple reason that nobody in the Mossad’s London station could say how well Marwan spoke English.

The meeting was set for the evening hours. London-based Mossad operatives took up positions outside the hotel to make sure it wasn’t a trap. Shmuel Goren, the director of the Mossad’s European operations, sat on a couch in the lobby, pretending to read a newspaper as he kept his eye on the entrance. The paper hid from view a photograph he was holding of Marwan. Dubi stood off to one side, keeping eye contact with Goren.

They didn’t wait long. At precisely the time they had set with Marwan, he entered the lobby, carrying a black briefcase. Dubi immediately recognized him from the description he’d received: tall, slim, dark. Goren thought he recognized him as well but wanted to be sure. He glanced at the photo and back at the man. The photograph was from Ashraf and Mona’s wedding four years earlier and was clipped from an Egyptian newspaper. Goren hesitated. Another look at the photo, and then again at the man who stood in the lobby, and that was enough. He looked at Dubi and nodded slightly. Marwan stood tense as Dubi walked up to him, extending his hand and smiling.

“Mr. Marwan,” he said to him quietly in Arabic. “It is a pleasure to meet you. My name is Alex.”

AFP Ashraf Marwan in London toward the end of the 1990s.

The young Egyptian was visibly surprised by the Arabic. He, too, worried that a trap had been set by the Egyptian secret police. He replied in English, “Are you Israeli?”

Dubi switched into English as well, confirmed that he was Israeli, and tried to calm the fellow’s nerves. They exchanged a few more words, and Dubi suggested that they go up to a room where they could talk. Marwan nodded his assent. Goren, who was not far from them, took a deep breath of relief when he saw them walk toward the elevator. The initial contact had gone off without a hitch.

Up in the room, Marwan felt considerably more at ease and led the conversation. He asked Dubi if he knew who he was. Marwan began describing himself at length, his public stature, his marriage to Mona, his relationship with Nasser and Sadat and the fact that he worked in the information bureau in the president’s office. He slightly overstated his importance.

For Dubi, the more interesting question was not Marwan’s status or his relationship with Nasser’s successor, but what kind of information crossed his desk. He raised the point carefully and politely. Marwan smiled, almost boastfully. He explained that the most important information in all of Egypt was concentrated in the hands of his boss, Sadat’s chief of staff. Dubi asked him to be more specific. Was it political information? Military or diplomatic? Relations with the Soviets?

Marwan had been waiting for the question. Picking up his suitcase, he produced a number of pages of handwritten Arabic and told Dubi that he was handing over, as a kind of down payment, something of great interest to Israel. He began reading aloud. Dubi, who had some understanding of military affairs, realized that Marwan was giving over details from a top-secret memorandum cataloging the Order of Battle of the entire Egyptian military. Dubi began quickly writing down the details of units, their location, commanders and equipment at their disposal. Occasionally he would stop to ask Marwan to clarify one point or another. When Marwan finished reading, the Mossad officer looked over the list. It was incredible.

'Material like this, from a source like this ― it’s something that happens only once in a thousand years.'

When he was done, Marwan handed him a manila envelope containing one final document. Dubi placed it in his briefcase without opening it. Marwan nodded his approval. To this day, no one recalls, or is willing to divulge, what exactly was in the envelope.

Dubi returned to his office and reconvened with his Mossad colleagues. They began plowing through the pages Marwan had given over. Goren looked up from the document he held in his hands and said, “Material like this, from a source like this ― it’s something that happens only once in a thousand years.”

Discussions over whether or not to pursue the services of Ashraf Marwan ― if he could be trusted, whether or not he had been sent as a double agent ― moved quickly back in Israel, and top Mossad officials eventually agreed to move forward.

Ashraf Marwan’s early code names included “Packti” and “Atmos.” The one that stuck, however, was “the Angel.”

Stringer/Getty Images Israeli Prime Minister Yitzhak Rabin, attends an army parade at Mitla Pass in the Sinai of Egypt on March 3, 1975. The event too place on the site of major battles between the militaries of Egypt and Israel.

In September 1973, Marwan, who by then was a senior advisor to President Sadat, met his Mossad handlers and passed on information related to Egypt’s preparation for war with Israel. The real focus of the meetings, however, was on something different: the prevention of what was very nearly the worst terror attack in Israeli history.

In Muammar Gaddafi’s moral worldview, the most fitting eye-for-an-eye response to Israel’s downing of Libyan Airlines Flight 114 would be to shoot an Israeli airliner out of the sky. He said as much to Sadat in April when the latter visited Libya. When the Libyans and the Egyptians began plotting the revenge attack, around July, the first question was where and how such a plane could be downed.

The planners quickly settled on Rome’s main airport, Leonardo da Vinci–Fiumicino Airport. On Marwan’s orders, two senior Egyptian security officials traveled to Rome to learn the layout of the airport, the flight paths and the best locations for attacking planes that were taking off or landing. They returned with blueprints and maps, and a plan was hatched for shooting down an El Al Boeing 747 passenger jet ― which seats around 400 passengers ― just after takeoff, using SA-7 Strela personal antiaircraft missiles that the Egyptians had just received from the Soviet Union. It was agreed that Egypt would take responsibility for delivering two missiles to Rome, where they would be picked up by Palestinians belonging to the Black September group ― the same organization that had murdered 11 Israeli athletes at the Munich Olympics the summer before.

The Sydney Morning Herald via Getty Images A Palestinian terrorist peers over the balcony of a room in the Olympic Village, where Israeli athletes were being held hostage, in Munich on Sept. 5, 1972.

The first part of the operation went off without a hitch. On August 29, Amin al-Hindi, the leader of the Black September squad, arrived in Rome to prepare the attack with four other members of his group. A few days later, on Marwan’s orders and without involving anyone from the Egyptian military, two missiles and their launchers were transferred from army stockpiles to Sadat’s office. They were packed in diplomatic baggage under the name of Marwan’s wife, Mona. She had planned on flying to London on an unrelated matter, but at her husband’s request, she agreed to meet up with him in Rome. Mona was completely unaware of both the plan and the contents of the bags.

As expected, the Italian authorities didn’t open them. Mona was Nasser’s daughter, and because the bags carried her name, they were taken directly from the aircraft to a waiting pickup truck, which transported them to the Egyptian Art Academy in Rome.

Marwan arrived in the city the following day. He put the bags in his private car and drove to the Raphael Salato shoe store at 149 Via Veneto, in the main shopping district. Al-Hindi was waiting in the store. He recognized Marwan from a photograph he had been given. He approached Marwan and said the code word ― several times.

In Gaddafi’s moral worldview, the most fitting eye-for-an-eye response to Israel’s downing of the Libyan passenger airliner would be to shoot down an Israeli airliner.

From there, however, things went slightly awry. Marwan told Al-Hindi that he and his men would have to take the missiles out of his car, transfer them to their vehicle and take them back to the apartment Al-Hindi had rented in Ostia, near the airport, from where the attack would be launched.

The trouble was, they didn’t have a car. They hadn’t been told they would need one.

The resourceful terrorists would not be deterred. They found a carpet dealer down the street, bought a few rugs and rolled up the missiles and launchers into them. Then they carried them on their shoulders to the nearest subway station. They used public transportation to take the missiles to Ostia. Al-Hindi stayed in the apartment while the others headed for the Atlas Hotel, a downtown dive that doubled as a brothel.

None of it would matter. The Mossad was fully aware of the scheme from the early planning stages, thanks to Marwan. But unlike his other work for Israel, this time he wasn’t really going against Egyptian interests. On the contrary, Sadat didn’t want the plot to actually succeed. This was just a month before he planned to launch his surprise attack against Israel. Shooting down an El Al plane would have triggered a massive regional crisis, and the discovery of SA-7 missile shrapnel among the wreckage would have implicated Egypt. Tensions would have risen dramatically and Egypt would have lost the element of surprise. Such a scheme, in other words, could completely scuttle Sadat’s plans for an attack on Israel.

Marwan knew Sadat’s thinking. Sadat had learned to respect Marwan’s stunning variety of talents, skills and connections. He would know how to ensure the mission’s failure, presumably by tipping off the Italians. But he never suspected that Marwan’s contacts were Israeli.

Bettmann via Getty Images Sadat, left, and Gaddafi look over a communiqué after agreeing to merge their two countries on Sept. 7, 1973.

In advance of the operation, Maj. Gen. Zvi Zamir, the chief of the Mossad, arrived in Rome to update the local authorities on the plot and to oversee operations in the event that the Italians failed to stop it. In part, Zamir was responding to the trauma of the previous summer, when German police had botched an attempt to rescue Israel’s Olympic athletes. Zamir had stood by in the control tower at the Munich airport, helpless. After returning to Israel, deeply shaken, he realized that the Israelis could not rely solely on local forces to protect its citizens abroad.

Indeed, this time the Israelis did not count on the local security services alone. Upon learning about the planned terror operation, more than two weeks before it was to take place, a Mossad team headed by Mike Harari, a senior and veteran operations officer, arrived in Rome. The team thoroughly searched the area around the airport, looking for hideouts that could be used to launch the missiles. Even more important, they followed Marwan when he transferred the missiles to the Palestinian terrorists in Via Veneto, and then followed the terrorists who took the missiles to their hideout. Harari wanted to raid the apartment but Zamir, who had already arrived in Rome, decided instead to tip off his Italian counterpart, with whom he had an excellent working relationship. Zamir’s only request was that the Italians give the Israelis one of the Strelas, with which the IAF was unfamiliar at the time.

Zamir’s Italian counterpart couldn’t conceal his surprise when Zamir told him he was in Rome to prevent a large-scale terror attack. This time, the locals did their job well. They organized quickly, and in the early morning hours of September 6, a large force of police entered the apartment in Ostia and arrested Al-Hindi. The other men were picked up downtown at the Atlas Hotel. Al-Hindi later testified that he was surprised by the size of the force, at first thinking the officers were Mossad. In reality, the Mossad team under Harari was ready to intervene in case the local forces faced problems, but there was no need for that.

Zvi Zamir Zvi Zamir, director of the Mossad from 1968 to 1974, at his home near Tel Aviv in the early 1970s.

The five terrorists were arrested. The missiles were confiscated, and the 747 carrying 400 or so passengers that had been the intended target of the attack went on its way without the passengers knowing what had happened. Zamir and his men returned to Israel. Although the Black September plotters were later tried, the Italians feared reprisals, and the men were released and allowed to leave the country.

When Marwan learned of the arrest of Al-Hindi and his men, he headed straight for the airport. Zamir did not tell the Italians who his source had been. Publicly, the question of how the Italians found out about the planned attack remained unresolved ― though the following headline appeared in one of the papers: “Italian Sources: Arrest of ‘Shoulder-Launched Missile Terrorists’ Came After Hints from Israeli Intelligence.”

Clarification: This story has been amended to reflect that while Saladin was a leader of the Arab world, he was Kurdish, not Arab.

Adapted from “The Angel: The Egyptian Spy Who Saved Israel,” by Uri Bar-Joseph. Reprinted with permission of Harper, an imprint of HarperCollins Publishers.

This was produced by The WorldPost, which is published by the Berggruen Institute.