Anny Boukris was just a child when the soldiers came knocking at the door. The year was 1942, and German troops were occupying her town and her homeland of Tunisia. Boukris lived with her parents, Jacob and Odette, in the seaside town of Mahdia, along its eastern shore. She and her brothers and sisters wanted for nothing. Jacob, a Jewish businessman, was doing well; they could even afford a maid.

All that changed with the fist at the door. Since the arrival of German troops that year, the family had suspected something would happen. They had stocked up on food, packed their family heirlooms into a boxroom and placed a bookcase in front of the door.

All to no avail. The soldiers inspected the house, found the hiding place and took all their precious belongings. Anny minded her stamp collection being confiscated.

Their house was being requisitioned as a barracks, the soldiers said, and they had only an hour to leave. Anny’s father kept his wits about him. He quickly arranged for his family to find refuge in an old factory nearby. Aunts and uncles joined them, and although the living conditions were far from satisfactory for everyone, they all felt safe enough.

A few weeks later came another knock at the door. This time the caller was no German but a local man, the son of a wealthy landowner. “You are all at great risk,” he told them. “You must leave straight away.” In the middle of the night he drove them to his farm, about 20 miles away. There they stayed hidden for four months, until the Germans had been driven out of the country and they could return home. It was only then that Anny came to understand the significance of the rescuer in the night.

The man was 32-year-old Khaled Abdelwahhab, a prominent and well-connected Arab from Mahdia, who made it his business to fraternise with German officers so he knew what was going on. Handsome, sophisticated and educated in the West, he made an agreeable companion and would sit drinking with them into the early hours. He knew, for instance, which brothels they frequented, which females they lusted after. He had also heard tales of local girls, many of them Jewish, being abducted for sex and never being seen again.

One night, one of the soldiers confided to him that he had his eye on a beautiful Jewish woman with blonde hair and blue eyes, whom he was going to take away “for his own pleasure”. When Abdelwahhab realised that the blonde he intended to rape was Anny’s mother, Odette, he sprang into action. He plied the soldier with drink, and when he eventually fell into a stupor, Abdelwahhab drove directly to the farm and whisked everyone to safety. “We left like that,” Anny recalled. Abdelwahhab, who later married and had a daughter, became a lifelong friend of the Boukris family. Forever an honoured guest, he was always invited to celebrate the sabbath with them, sitting down to share chicken couscous and memories. There, around that table, they would talk of the war. Arab and Jew shared a special bond.

Abdelwahhab’s heroism in saving Odette from abduction and rape – and rescuing her entire family from persecution and possible death – would have been forgotten were it not for the efforts of one remarkable historian of the Middle East, Robert Satloff. A 44-year-old American of Jewish descent, he has devoted the past four years to searching out lost heroes of the Holocaust. Not just any heroes, but Arabs such as Abdelwahhab. “He could so easily have been killed if the German officer had found out that he had tricked him to save a Jewish woman,” he says. Executed swiftly, perhaps, or tortured to death in any of the 104 “punishment” camps then being built across the Sahara.

Satloff’s quest for good men took him not to Europe, where 6m perished under the Nazis and where virtuous men like Oskar Schindler and Raoul Wallenberg risked everything to save lives, but to the shores of North Africa, where France’s possessions of Morocco, Tunisia and Algiers – and its Jewish population – had fallen to the Germans.

“We all know the horrific stories of the Jews who died in Europe under the Nazis,” he says.

“I wanted to look at the long reaches of the Holocaust. Persecution was not just a European story. I wanted to investigate what happened to Jews living among Arabs when the Nazis arrived. Their stories have been overlooked for far too long.” He reminds us that had allied troops not driven the Germans from the African continent in 1943, then the 2,000-year-old Jewish communities of Morocco, Algeria, Tunisia, Libya, and maybe Egypt and Palestine too, might have met the fate of their brothers in Europe.

The result of his detective work, which drew upon scores of interviews with witnesses and survivors of pogrom, is contained in his newly published book, Among the Righteous. “I set myself a simple goal,” he says. “To tell the story of one Arab who saved the life of one Jew.” He had in his mind a saying from the Koran: “Whoever saves one life, saves the entire world.” This passage echoes the Jewish exhortation: “If you save one life, it is as if you have saved the world.”

Satloff, who runs the influential think-tank the Washington Institute for Near East Policy, began to dig in wartime archives and libraries but could find little about the half-million Jews of North Africa. There were bare statistics – nearly 5,000 were killed in air raids or as a result of forced labour – but few details. Questions hung in the air. What became of the Jewish families in Casablanca and Algiers when the tanks rolled in and the jackboots marched? What happened when Vichy, the collaborationist government of Marshal Pétain, brought in anti-semitic laws?