I found the box that contained the puzzle pieces of my family’s past on the day of my father’s memorial service. It was early January 2002 and I’d flown from London back to Caracas, the city I grew up in, to mark my father’s departure and collect his ashes. I walked into his study in our family home, still redolent with the smell of his pipe, to start the mammoth task of sorting through his copious archives. I was braced for the work ahead. My father had been a successful man, with a huge breadth of interests. He was a collector, a hoarder even. His rooms had always been laden with books, papers and letters. He’d kept every note or memo – no matter how trivial. Every receipt. But when it came to it, a job that I’d expected to take days took no time at all. My father had arranged for his study to be cleared out before his death. All that remained was a yellowing folder containing every note I’d ever sent him, the love letters he’d received from my mother, and the old grey cardboard box, which I’d only ever seen once before, and had long forgotten. As a little girl, growing up in 1970s Caracas, I longed to be a detective. Inspired by tales of Enid Blyton, I set up a secret society with cousins and friends to spy on the adults. One day, my cousin reported that my father had moved a mysterious box file from his workshop to the library. I waited for my fellow detectives to leave and found the box. It contained a few sparse papers, but my eye was caught by an aged pink identity card showing my father’s 20-something face but bearing a completely different name: Jan Šebesta. It made no sense. My father’s name was Hans Neumann. I knew my father to be from Prague but this read Berlin, 1943. I was terrified. I ran, sobbing, to my mother’s bedroom, where she stroked my hair and tried to soothe me. ‘Your father had a very difficult time in the war,’ she explained. ‘He had to use a different name.’ My mind had raced with questions, but my mother told me not to press him further about it – ‘It will upset him,’ she said. And so I didn’t. My father was different from my friends’ parents – older, more serious, always working, prone to nightmares. On arriving in Venezuela in 1949, he’d started a paint factory and by the time I came along, he was a well-known industrialist and intellectual. I was always immensely proud to be his daughter and yet, somehow, there was a part of him that was closed, even to me. Years passed and I grew into a teenager – far too concerned with myself to pursue more questions about where he’d come from. The memory of the box receded until suddenly, with my father now gone for ever, I found it again. And this time it was crammed with papers. Slowly, I realised that he had left me the box as a riddle for me to unlock, giving me his implicit blessing to explore his past and find out who he, and my family, had been. He’d left it as a puzzle because we had always liked to solve puzzles together, and because he could not tell me – or anyone – the story in its completeness. That box contained papers, photographs and objects from the war and the life that he had never been able to share with me. I knew that the story they told would be painful and as a mother to three young children, it took me a long time – years, in fact – to feel ready to uncover its truths. But in 2011 I finally decided to plunge forward for better or worse, and set off on a journey that has led to more boxes, more people, more photographs, more bravery and more tragedy than I ever imagined. With the help of researchers, I spent 2012 to 2018 laboriously piecing together fragments, corroborating evidence and, often literally, retracing my father’s footsteps in order to discover the family and life he’d known before and during the war. What I found astonished me. Far from being the man of iron discipline that I knew, the young Hans was an aspiring poet and incorrigible prankster, always late and usually to be found merrily wasting time with his best friend Zdeněk. He had enjoyed a carefree life in 1930s Prague. His well-to-do father Otto owned and ran the Montana paint factory. His delightful mother, Ella, kept a close and happy eye on her two sons. The letters and photos from this time suggest that life retained a degree of surprisingly jolly normality. Hans was in his late teens by this point, mad about art but wearily fulfilling his father’s wish for him to study chemistry at technical college. Nevertheless, the tide of anti-Semitism surged around them. Between 1933 and 1939, 1,400 anti-Jewish laws were passed in neighbouring Germany and by 1937, open discrimination and even violence against Jews in Prague became a regular occurrence. And yet the pictures from that time show a family that was relentlessly focused on the positive – they worked, studied, spent weekends at their country home in Libčice. They travelled and laughed. And yet all the time the net tightened. On 16 March 1939, a triumphant Adolf Hitler rolled into Prague and claimed that Czechoslovakia had ceased to exist. Their entire world was to change. The following year, control of the family business was seized by a Reich-appointee, who was summarily deemed legal owner of the company. A year later, in 1941, the transportations of Jews to the labour camp at Terezín began. My father’s parents were themselves transported to Terezín – Ella in May 1942 and Otto six months later. On both occasions, Hans’ own name appeared on the summons for the transports but both times, he engineered a last-minute reprieve. Those twists of fate undoubtedly saved my father’s life. And yet they also instilled in him a guilt and heaviness that he could never relinquish. When the inevitable third summons arrived, Hans’ luck appeared to have run out. My grandparents had succeeded in arranging for letters to be smuggled out to their sons. The dire conditions at Terezín were brutally clear. There was only one option, Hans would have to run. In Otto’s absence, Hans’ older brother Lotar was working in the paint factory, under the hostile eye of its new controller. He benefitted from a measure of protection, having married a non-Jewish woman and he had managed to obtain false papers that didn’t bear the ‘J’ stamp that identified all Jews. Desperate at the thought of his only brother being sent to Terezín, he set out with a trusted colleague to secretly construct a false wall in a small storeroom at the factory. The plan was that Hans would hide silently inside the tiny cavity during working hours and then, as soon as the staff had some much-needed fresh air. This would at least buy precious time. On 9 March 1943, the Gestapo was notified that Hans had not registered for his transport. He was officially an absconder. He was placed on the SS wanted list in Prague and his life was now truly at stake. He spent months, day after day, holed up in that tiny space. He spent the daytime hours straining to read books and writing letters in the gloom and silence. He had only a handmade good luck doll for company – a doll that was waiting for me inside the box almost 60 years later. In early April, Hans’ friend Zdeněk visited Prague and Lotar brought him to the factory. Like many non-Jews, Zdeněk was forced to work as a labourer for the Reich. He had a job at a paint factory in Berlin, supplying the Luftwaffe. During their whispered, candlelit exchange, Zdeněk complained of how busy they were and bleakly joked that he wished Hans could come and work alongside him. But my father didn’t laugh. Absorbed by the candle’s flame, he simply murmured an old Czech saying: ‘The darkest shadow lies beneath the candle.’ Zdeněk instantly knew that my father was airing a dangerous plan to try and live among the Nazis in Berlin. He thought the notion insane and told him so. But the thought had lodged in my father’s contrarian mind and he would not be talked out of it. He was being hunted in Prague. His pursuers would never think of looking in the German capital; no Jew on the run would ever choose to hide there. If he could travel to Berlin, the heart of the Reich, just beneath the candle where the darkness was the greatest, the Gestapo might never find him. There, in the centre of it all, he could hide in plain sight. In the fevered weeks that followed, Hans and his tiny coterie of friends and family set about constructing a cover for him. They forged various papers in the made-up identity of Jan Šebesta, the name on the card that had terrified my eight-year-old self and sent me crying into my mother’s arms. Also among the papers my father left me in the box were two-dozen typed sheets – early workings of a memoir that he started but never finished. These sheets are now among my most precious possessions – a direct connection to what happened to my father next, told in his own words. He describes the train journey he made to Berlin on 3 May 1943, armed with the Jan Šebesta ID card and Zdeněk’s Czech passport. It had proved impossible to forge a new passport so, in a huge act of love and supreme bravery, Zdeněk had lent him his own. All my father could do was hope that only one form of identification would be checked at the German border. It was a colossal risk. As the border guard requested his papers, my father held a small vial of cyanide between his teeth – ready to bite down the moment his cover was blown. Thankfully, it was not. My father’s audacious plan had worked. He spent the rest of the war alongside Zdeněk, as the quiet, unassuming chemist Jan Šebesta, working in the paint factory in Berlin. As a Czech man, the Nazi regime, with its obsession with racial classification, considered him a ‘lapsed Aryan’ who was usefully contributing to the Reich’s regime. This meant that while he was discriminated against, he was treated better than the Russians or Poles who were deemed subhuman. The constant pressure of living among the enemy must have been excruciating. He had to watch his every word, his every step, so as not to arouse suspicion. He was recruited as a firefighter, which meant that when his day job finished in the factory, he had to spend his nights tackling blazes and rescuing German civilians from the Allies’ bombing campaigns. Between 1943 and 1945, hundreds of thousands were killed in Germany by the RAF and US Forces as raid after raid dropped tons of explosives and incendiaries on German cities. It would have been impossible for my father to know what to wish for – more bombardments that heralded death but also the defeat of Germany, or a reprieve from the endless bombing. When the chaotic end of the war finally did arrive in early 1945, my father made it out of Berlin – just. He arrived back in Prague in an old striped shirt, trousers and tennis shoes. No socks and no suitcases. He carried just a small valise containing his papers, the vial of cyanide and the good luck doll he’d had with him since the days he’d spent encased in the wall cavity at the paint factory. Reunited with his brother Lotar, he then had to face the agony of discovering that 29 of their relatives had been deported to concentration camps; their beloved parents Ella and Otto were sent to their deaths in Auschwitz in the autumn of 1944. I’ve spent the past eight years piecing together these stories of death and survival, and bringing them together in a book. It has been the greatest challenge and proudest achievement of my life. The evidence shows me that, despite the Nazis’ systematic attempts to dehumanise them, my grandparents went to their deaths with their hope and love for their family intact. My father’s ability to adapt and survive is testament to the resilience of the human spirit, and discovering what happened to him has enabled me to understand why he was the way he was. I now know the stories that he was unable to tell me himself, and I feel closer to him than I did while he was alive. I’m so grateful he left me that cloth-covered box so that I could finally discover the truth. When Time Stopped: A Memoir of My Father’s War and What Remains, by Ariana Neumann, is published on 20 February (Scribner UK, £16.99)