On a chilly afternoon in late October 1942, Arthur Gachet, having overseen the first Lysander missions to Alliance, arrived in Marseille for a meeting with Fourcade. As he left the Saint Charles train station, he spotted a familiar face—someone he had met during an MI6 training course for radio operators a couple of years before in London. His former colleague recognized him, too, and seemed delighted to see him.

The man told Gachet that the resistance group to which he had been assigned had been destroyed by the Gestapo, that he had barely escaped, and was now looking around for another network to join. He mentioned the fact that the head of the defunct group had been a woman.

Gachet immediately realized to whom he was speaking: Arthur Bradley Davies, also known as Bla, the former Alliance radio operator suspected of selling out more than a dozen agents in Paris and Normandy to the Germans the year before. Even though MI6 had assured Fourcade in late 1941 that Bla had had nothing to do with the arrests, she believed otherwise and, with the help of some of her men, had set out to prove his guilt.

In the early spring of 1942, Maurice Coustenoble, Fourcade’s adjutant at the time, had uncovered a key piece of evidence that supported her suspicion. He’d made the discovery during a trip to Paris to investigate the possibility of organizing an escape attempt by the jailed agents from Fresnes prison, a massive gray fortress-like structure near the French capital that held hundreds of resisters. After several days of casing it from the outside, Coustenoble gloomily concluded that unlike Vichy jails and prisons, whose guards often could be bribed or were anti-German themselves, Fresnes was so impregnable that a successful escape attempt was impossible.

But during his reconnaissance mission, Coustenoble also found that several of his imprisoned colleagues had smuggled out messages to their families, hidden inside parcels of soiled clothing that were laundered by family members and returned to Fresnes. Most of the messages detailed the extraordinarily harsh treatment the Alliance agents had received, including several instances of torture. But a message from Lucien Vallet, Fourcade’s former radio operator, provided the first bit of concrete evidence of Bla’s treachery. During an interrogation by the Gestapo, Vallet wrote, he had been shown the very radio set he had been using before his arrest—a set that had been spirited away by another Alliance agent before the Germans could find it and had been delivered by the agent to Bla.

Fourcade immediately passed on Vallet’s report to MI6 headquarters, which replied that Bla was still sending excellent information from Normandy and reiterated that she was mistaken about his guilt. This time, however, she refused to give up and dispatched yet another message arguing her case. MI6 failed to respond for several days. Then one morning, a top-priority message landed on Fourcade’s desk, with instructions to decode it at once. In it, MI6 officials acknowledged that Bla was indeed a traitor who had worked for the Germans. They ordered Alliance to execute him.

Not until months later did Fourcade find out that MI6, thanks to her pressure, had finally conducted an investigation into Bla’s past. In doing so, the agency discovered that he had been a member of the British Union of Fascists, founded by Oswald Mosley, a former member of Parliament who’d been arrested and jailed by the British government in 1940. MI6 officials came to the conclusion that Bla had been working for the Germans the entire time he had been in France. They immediately sent a cable ordering him to hide his radio set and travel to neutral Spain or Switzerland, where he was to report to British authorities. He never responded. It was then that the agency decided that because he was personally acquainted with leading members of Alliance, the danger to the network was grave enough to warrant his execution.

Eddie Keyser suggested that Fourcade try to set up a meeting between Bla and one of her top agents in Lyon, with the idea of executing him there. She agreed, and a message was sent to Bla in Normandy telling him to appear at the rendezvous on a certain date. When the Alliance agent showed up at the appointed place, Bla was nowhere in sight; German military police, however, were there in force. The agent barely escaped.

For the next several months, Bla’s trail went cold. There were reported sightings in Pau and Toulouse, but to Fourcade’s frustration, no solid leads regarding his whereabouts—until Gachet’s chance encounter with him in Marseille.

During their brief chat, Bla asked Gachet if he could help him get a job with another network. Gachet said he would see what he could do and arranged to meet him the following night at a bar in Marseille. The next morning, Léon Faye burst into La Pinède and told Fourcade about Gachet’s spotting of Bla and the scheduled rendezvous. He insisted that she stay away, and she agreed to let him take charge of Bla’s capture and interrogation.

At the bar that evening, Gachet told Bla that the head of his network was anxious to meet him and had asked Gachet to bring him to the network’s headquarters. Shortly after they left the bar, two men in raincoats, their hats pulled down over their eyes, stopped them on the street. Identifying themselves as Vichy police, they asked both for their papers. Gachet strongly objected, but Bla readily handed over an identity card that bore his real name, an address in Paris, and his nationality as a British subject. One of the policemen said they needed to check out his story and ordered him to come with them.

Gachet again objected, but Bla told him to be quiet, then handed the policeman a piece of paper with a phone number scribbled on it, saying that if he called the number, he’d find out that everything was all right. The number, it later turned out, was that of the Abwehr headquarters in Paris.

The policemen hustled Gachet and Bla into a waiting car, which raced through Marseille’s narrow streets, skirted the port, and headed along the Corniche for a mile or so before stopping at a building a few blocks from the coastal road. Once inside, the policemen’s courtesy vanished; they shoved Bla into a brightly lit room, where Gabriel Rivière stood, pointing a gun at the Englishman. Léon Faye, who was next to Rivière, grabbed Bla by the lapels of his jacket and barked, “We’ve got you at last!” Bla looked around the room in panic. The two “policemen” had taken off their hats and coats, revealing themselves to be Alliance operatives as well. Bla told Faye he’d made a mistake, that he was not the man Faye thought he was.

For more than an hour, Faye battered Bla with questions, but he insisted again and again that Faye and his colleagues were mistaken. None of the Alliance agents in the room had been in Pau when Bla had arrived by parachute in the spring of 1941; Fourcade was the sole member of the network in Marseille who could positively identify him. Although Faye had wanted to keep her involvement in this whole sordid business to a minimum, he reluctantly asked her to come to the office where Bla was being held, saying she was the only one who might be able to get him to talk.

When she entered the bare, smoke-filled room, lit only by a single unshaded bulb overhead, Bla recoiled in shock. Earlier, Fourcade had told Faye that although Bla should not be mistreated during his interrogation, he should be forced to stand throughout. He continued to do so as she questioned him, with only one other agent, who kept a gun trained on him, in the room. Bla readily admitted to her that he had indeed been a member of Oswald Mosley’s fascist party and had offered his services to the Abwehr in Paris shortly after leaving Pau. On the Abwehr’s orders, he had infiltrated Alliance’s sector in Paris, worming his way into its agents’ confidence and setting up their arrests.

When Fourcade asked if he had ever been in Normandy, he replied that he had rarely gone there. His radio set, which MI6 believed was being operated from there, was in fact at the Abwehr’s Paris offices. He did the actual transmitting himself, since each operator had his own distinctive style and he didn’t want to arouse any suspicions within MI6. Much of the information he sent was genuine although relatively unimportant, he said. Occasionally, though, the Germans slipped in a bit of false intelligence to send MI6 on a wild-goose chase. He’d come to Marseille on behalf of the Abwehr, he added, to find out where she was.

As forthcoming as he was about his activities in Paris, however, Bla fell silent when Fourcade asked him about his contacts in London. When he had first come to Pau, he had boasted to her brother that he had a secret high-level connection in the British capital. But when she mentioned that, he refused to say anything more. Exhausted, Fourcade finally gave up. Finding Faye in an adjacent room, she said that Bla had confirmed everything they already knew but had revealed little else. He told her to go back to La Pinède, adding that what happened next didn’t concern her.

Knowing that MI6 had confirmed the execution order for Bla earlier in the day, she asked Faye what he was going to do. He produced a packet of white pills from his pocket, saying he had been given them in London. Fourcade knew what they were: cyanide tablets issued to MI6 and SOE agents operating in occupied Europe to use in case of arrest and interrogation by the Gestapo. Faye said they worked very quickly. Nodding, she told him she didn’t want Bla to know what was about to happen.

As the sun rose over the Mediterranean, she left the building and caught a tram back to La Pinède. Several hours later, Lucien Poulard, one of the agents involved in Bla’s capture, rushed into the villa. He was distraught, and it took Fourcade several minutes to calm him down. Despite two separate attempts to kill Bla, Poulard told her, he was still alive. “You can’t imagine what it was like,” Poulard said with a shudder, as he described the macabre scene from the beginning.

After Fourcade had left, Poulard, on Faye’s orders, had given Bla a bowl of hot soup in which he had dissolved a cyanide tablet. Also on Faye’s orders, Poulard joined Bla at the table, eating from his own bowl of soup so that Bla would not suspect that his had been tampered with. They began eating, but nothing happened. Finally, Bla complained of a stomachache and asked to lie down. Poulard agreed. After three hours, Bla was still conscious.

Faye told Poulard to try again, this time with a cyanide tablet dissolved in a cup of hot tea. Bla swallowed a mouthful, grimaced, and asked, “Is this an order from London?” Then he finished the tea and handed the cup back to Poulard with the remark, “It can’t be much fun for an officer to have to do this kind of thing.” Another two hours went by, and Bla was still very much alive.

Once Fourcade heard the story, she returned to the building near the Corniche, where she and Faye reluctantly agreed to a proposal by Rivière to recruit several gangsters from Marseille’s underworld, who were acquaintances of his, to help them dispose of the seemingly indomitable Bla. According to Rivière’s plan, he and the Alliance operatives would escort Bla late that night down to a small, secluded beach near the city’s Old Port, where the mobsters would meet them in a fishing boat. After boarding the boat, Bla would be taken several miles out to sea and then thrown overboard.

Again, Fourcade headed back to La Pinède, where she spent a sleepless night. Staring out a window early the following morning, she saw Faye’s tall, slightly stooped figure approaching the door. Without a word, he opened it, flung himself down on a couch in the ground-floor office, and began to tell her the latest chapter in this ongoing ghastly comedy of errors. The gangsters had failed to show up, and Bla was still alive.

They had waited for hours on the beach, Faye said. As the time crept by, he began losing his resolve to get rid of Bla. When Rivière told Faye that the gangsters obviously weren’t coming, Faye ordered everyone, including Bla, to return to the Corniche.

Fourcade realized that Faye was having a crisis of conscience, and she understood why. Like many of his Alliance colleagues, he was a career military officer, a toughened veteran of World War I who had never quailed at the thought of killing the enemy. But the cold, deliberate execution of a former colleague, even one who had admitted to betraying his comrades, was harder to stomach.

“You’re exhausted, and your men are worn out,” she told him. “To [them], this villain will soon seem like a nice person. They’ll pity him, whereas he is in fact an enemy.” Bla, she declared, must be put on trial for espionage: “We have the right to do so, and it’s our duty.”

A few hours later, she, Faye, Rivière, Lucien Poulard, and two other operatives sat around a large table in the room where Bla was being held. He was placed in a chair facing them. Faye, who presided over the improvised military tribunal, stood and read a lengthy indictment. When asked to respond, Bla said that all the allegations were true; he was indeed a German spy. Faye then condemned him to death. At that point, Fourcade left the room, returned to La Pinède, took a strong sleeping pill, and went to bed.

Bla’s fate was never made public. There was some talk after the war that Faye had been unable to go through with the execution and allowed Bla to flee to North Africa, where he settled down with his wife and children. In fact, Bla’s wife never saw him again. In late 1944, when she made inquiries to British authorities about his whereabouts, she was told that her husband had been turned by the Germans and, when found out, had committed suicide.