To know your mother was raped multiple times and obliged to suffer unspeakable humiliation to survive the Holocaust is bad enough. To hear her tell the story chapter and verse and then relive her painful experiences while assembling them into a book must be excruciating.

But that is what Hermann Simon did to honour his mother, Marie Jalowicz Simon, who led an extraordinary few years in her native Berlin during the War. She found a way to fool the Gestapo when they came for her, flitted fearlessly to and from Berlin during periods of hiding outside the city and declared unashamedly that she could not identify with the mindset of a community resigned to going meekly to its death.

A controversial figure who was extremely free-thinking for her time, Marie stayed on in Berlin after the war and became a Professor of Philosophy. Anything but assimilated, she clung ferociously to the Jewish way of life in which she raised her son and daughter with her husband, Heinrich Simon: "She was never going to marry a man who wasn't Jewish," says Hermann of the many resolutions Marie made as she walked barefoot, dragging her few possessions in a handcart, back to Berlin free and proud after the city was liberated.

She had spent the past three years enduring the unwanted attentions of men who took advantage of her. But she was astonishingly pragmatic: "I was visited by a sturdy, friendly character....I didn't mind too much," she says of the Russian soldier whose label "my fiancee", pinned to the door of her room after taking his pleasure, kept out fellow soldiers with the same intent.

Then there were the husbands of family friends who took her in for a couple of weeks at a time and knew she was not in a position to protest, and even a rabid Nazi she had been sold to, who happily for her was not fit enough to perform. It's a hair-raisingly frank story of survival- and it took 15 years for Hermann to be ready to share it with the public.

"The last of the tapes she left was made on September 4, 1998 and the book was published in Germany in March 2014," he says of Gone To Ground, which recently reached the UK in English translation. Hermann, now a director of Berlin's magnificent Neue Synagogue, insists he knew what he was in for when he broached the subject of his mother recording the story of her wartime experiences. It was a suggestion which was to produce 77 tapes of such vivid narrative, it's no surprise the book became an instant best-seller in Germany.

Marie, was 75 and seriously ill when her son approached her to make the tapes: "I'm quite sure she knew that she did not have long to live, and I had a strong feeling that she wanted to tell her story while she could," he says

But did the son not wince at all the graphic detail, which included at least one lesbian encounter? "As a historian, I was able to distance myself from the content and place myself in that role first and foremost, not so much in the role of a son," explains Hermann, a specialist on the history of Jews in Germany.

"The revelation of the intimate facts my mother spoke of was not so hard for me to hear because it was within the context of her struggle to survive."

The book is bound to be seen as controversial here because it refuses to paint all Nazis as villains, only their philosophy. Marie credited her survival as much to the kindness of a few "good" Nazis she encountered - like the foreman at the Siemens factory where she took satisfaction in performing "many small acts of sabotage" during forced labour - as to the many anti-Nazis who took her in at enormous danger to themselves. Knowing forced labourers were forbidden from resigning, the foreman agreed to fire Marie when she explained she needed to plan how to save herself from deportation.

Of course it helped to be young and beautiful, and Marie was genuinely in love with Ernst Wolff, the Jewish lover 30 years her senior who was taken by the Nazis, and for a while with Dimitr Tchakalov, a Bulgarian she met in Berlin and with whom she fled to Sofia, originally intending to continue beyond the Bulgarian border to Turkey and then to Palestine.

But one of the extraordinary twists in Marie's story is that she returned instead to Berlin, her strong city accent helping her to blend into the crowd. She walked the length and the breadth of the city streets from 1938 onwards, preparing herself for a life in hiding by ripping off her Jewish star whenever she was in a neighbourhood where she was unknown, and keeping a threaded needle in her pocket to sew it back on within seconds before returning home.

The book came about when Herrman felt it vital to flesh out the snatches of fascinating facts Marie dropped into conversation with him and his late sister Bettina. "She would talk about how she had survived from time to time, but often we didn't know why she told a story, and I found it frustrating that I knew so many other people's stories in detail but not of how my mother survived. I imagined that it would be extraordinary, because she was very strong-willed, with a razor-sharp intellect and an extraordinarily clear memory."

Marie first submitted to unwanted sex as a schoolgirl of 16 in 1938, the only child of a family already dispossessed: "If we didn't want to be turned out on the street...I must do something - which meant making myself available to the woman's husband," she says of their Jewish landlords. "I had some sexual experience already, and I thought: what does it matter? Let's get it over and done with."

With the handsome Bulgarian who wanted to take her home she slept willingly, got pregnant and induced a miscarriage to make herself ready to flee the country. She got out of Germany with the help of a family friend who lent her own identity for the duration of the war, but fell out of love and ended up back in Berlin. After a few months of moving from one hiding place to another, the Jewish doctor Benno Heller who saved many Jews arranged for a Dutchman to take Marie in as his "wife"; she spent the last two years of the war in plain sight, living as a non-Jewish housewife.

Marie clung fiercely to her religion, secretly saying kaddish for her friend Fritz Goldberg, also living openly in Berlin, when he was taken by the Nazis. Poignantly, she named the bench where they used to meet and talk for Weissensee, Berlin's Jewish cemetery, where she silently said memorial prayers.

So cinematic is the book, it comes as no surprise that Marie's story has a happy ending. Her old school friend, who had emigrated to Palestine, returned to Berlin and married her after the war, they had distinguished academic careers and two children. Sadly, Hermann's sister predeceased her mother, dying of an incurable illness, and the book was published only after Heinrich's death in 2010 - he had found listening to the tapes painful, admits Hermann.

But however breezy the writing - Marie took time to be brutally waspish about her Berliner intimates, and found humour in her encounters with them - make no mistake she paid a high price for making free with her body. "I was not shocked that she had to sell herself to survive," says her son of the "difficult" facts he persuaded his mother to reveal, "but it did make me very sad that she was at the mercy of so many unscrupulous individuals at such a young age."