At the beginning of his profoundly moving memoir of his grandparents, parents, the Holocaust and the Gulag, Daniel Finkelstein writes:

This the story of how my family took a journey which ended happily in Hendon, eating crusty bread rolls with butter in the café near the M1, but on the way took a detour through hell.

Who would have guessed what those people, tucking into rolls at the newly-opened Brent Cross shopping centre in the mid-1970s, had been through? There was Finkelstein’s elegant Polish-Jewish grandmother, Lusia Finkelstein, known locally as ‘the Lady of Hendon Central’ in her hat; his German-born Jewish mother, née Mirjam Wiener, a maths teacher, who particularly enjoyed reading books that argued against positions she held; and his father, Lusia’s only son, Ludwik, an engineering professor and quite formal man, who ‘always straightened his tie to answer the telephone’.

Lusia and Ludwik, from a wealthy family of Polish industrialists in Lviv, had survived the Gulag together. Mirjam, whose parents Grete and Alfred Wiener had moved with their three daughters from Berlin to Amsterdam in 1933 when Alfred had foreseen the danger to Jews in Germany, had survived Belsen.

To read Finkelstein, one of our great thinkers and writers, on the precise nature of those two versions of earthly hell and the exact process by which people came to be in them, is an unforgettable experience. This is a vital addition to the literature of two catastrophes of the 20th century. With great clarity and wisdom he demonstrates what evil politics can do. A document, a pact, is signed. Millions die. A sister writes what will be her final letter to her beloved sibling, cheerful and full of hope to the last, before boarding a train to death.

There is not a word of padding. In his acknowledgements Finkelstein thanks Robert Harris, who passed on to him Tom Stoppard’s warning to writers: ‘Just because something is true, it doesn’t mean that it is interesting.’ The prose, distilled into what is both true and interesting, can sometimes be disarmingly simple. Of the Wannsee Conference of 1942 Finkelstein writes: ‘The proceedings lasted an hour-and-a-half, during which the group agreed to murder all the Jews of Europe. Then they had lunch.’ Of the journey by cattle truck to the Westerbork transit camp in Holland, for hundreds of thousands of Dutch Jews the prelude to death: ‘Before living in hell, it is necessary to travel there.’

Ten days after Mirjam’s tenth birthday, ‘the time for the rucksacks finally arrived’. That Alfred, Mirjam’s father, had not taken his wife and children with him when he moved his Jewish Central Office from Amsterdam to London in 1939 is very hard to swallow. This dreadful error was done for the sake of the children’s ‘stability’. Alfred would spend the war in America, desperately trying to get his family to safety as well as collating his library of Nazi literature which would prove an essential resource for the Nuremberg trials.

With an astonishing mastery of complex material, Finkelstein shifts back and forth between sections on ‘Mum’ and ‘Dad’. Those of us brought up on the diary of Anne Frank (with whom the Wiener girls went to school in Amsterdam, and whom they would encounter again on the brink of death in Belsen) are already familiar with what life was like for Jewish children in Nazi-occupied Holland. Finkelstein augments our knowledge with a devastating account of happened to the (mostly Jewish) children who started a friends’ group called the Joy and Glee Club, of which his aunt Ruth was a founder member. The majority would perish in the gas chambers.

What I did not know enough about was the ordeal of the Poles swept up in the aftermath of the Molotov-Ribbentrop Pact. Finkelstein’s grandfather Dolu, a successful industrialist, his wife Lusia and their son Ludwik became Soviet citizens overnight. Being both Jewish and middle class, they were considered doubly ‘socially undesirable’ by the Soviets. Dolu was taken away to Siberia, subjected to torture and interrogations and forced to drag logs from forests, a human pack-horse in the frozen wastes, which almost broke him. Lusia and Ludwik went on a different cattle truck to forced labour on a Soviet state farm, surviving winter in an unheated self-built hut with no cooking facilities. Her determination to protect her son kept Lusia alive, and Ludwik’s own will to educate himself helped to save him. One evening, when Lusia arrived back in the hut through deep snow after a 12-hour day of making adobe bricks from cow dung, Ludwik’s first question to her was: ‘Mamusia, what is the difference between an anode and a cathode?’

Far above these dots of humanity, politics directed their futures. The German invasion of the Soviet Union would tweak the strings that enabled Dolu to join the new Polish Anders’ Army, and allow Lusia and Ludwik to walk away from the state farm to the nearest town, where they managed to scratch a living.

Meanwhile, in the ‘Mum’ story, Grete and her daughters, Ruth, Eva and Mirjam, having somehow dodged the Monday-evening lists of transports to Auschwitz, would move from the near-hell of Westerbork to the true hell of Belsen – which had initially been opened as a holding camp for possible exchanges with Germans, but which soon descended into an overcrowded stench hole of starvation, disease and piled-up corpses.

Then a miracle happened. ‘We are called,’ Ruth, the eldest daughter, wrote tersely in her diary on 20 January 1945. An eccentric system of rescue had got going in Switzerland, whereby a Polish diplomat, Aleksander Ładoś, issued fake Paraguayan passports to Jews. It all so nearly didn’t work. A tiny fraction of Belsen prisoners benefitted from the exchange of Jews for Germans. And the girls’ beloved mother Grete would die within hours of arriving in the safety of Switzerland.

Among the hundreds of details in this book I will never forget is this one. It demonstrates the lack of insight that people who weren’t caught up in the Holocaust had towards those who were. At her American school, just after the war, Ruth was set an essay entitled ‘My First Impressions of America’. In her already good English, she wrote: ‘I thought of my mother, who died after departing the camp.’ The teacher underlined the sentence, added a querulous question mark above it, and gave Ruth an A/B-minus.