It’s a tale of two worlds, of everyday lives upended by crisis. Here is a story that treads the edges of the Holocaust, a touching, and touchy and utterly dangerous business for writers of fiction.

Beginning in 1933, much of the tale is concerned with the Nazi persecution of the Jews in that darkening decade, the 1930s, when Rosa Klein is nine years old and Berlin is still a civilised city where Jews can transact their everyday business in relative tolerance and peace.

Yet, even then, as Rosa ventures to a bakery on an errand for Inga, her mother, clear signs of hatred and propaganda, the shutting down of normal decencies, are apparent. Rosa’s family belong to the trenchant middle class, with a stay-at-home mother, brother Heinrich and live-in maid. Otto, the father, is a well-regarded surgeon who won the Iron Cross in the First World War. He thinks of his family as staunchly German, only secondly Jewish. But when at work he is removed from contact with patients – “in the hospital we are attempting to create an Aryan atmosphere” – he knows the game is up.

His sense of fairness is affronted, his sense of identity undermined. His pride and stubborness — ingrained character flaws more jingoistically German, perhaps, than Jewish — lead to his downfall. When Wilhelm Krützfeld, a longstanding friend, and now the district chief of police, attempts to ensure that the Kleins receive preferential help to secure their safety in the face of the upsurge of anti-Semitic attacks, Otto refuses the offer of help, despite his wife’s pleading. Krützfeld’s wife is Inga’s best friend.

The tale unfolds to the drumbeat of history. Its dramatis personae feature real figures from the time, including Krützfeld and his wife, and, most importantly, the presence of Norbert Wollheim, the driving force behind the Kindertransport which rescued Jewish children from certain death and brought them to England before the war.

Rosa’s removal from her family (she’s then 15) is a pragmatic but also sacrificial act of parental love which brings her safely, and as an emissary, to London. It is the turning point in the novel.

Connoiseurs of crystal clear prose will relish this book as artless art.

One may be aware of the writerly presence of Jake Wallis Simons taking pleasure, a tactile relish, in the writing, with sentences gliding, weaving, slowing, speeding up, but always he carries the story deeper, making it resonate.

The Kleins’ demise, though touchingly tragic in its details, is partly transcended as the story moves beyond the plight of Jews in Nazi Berlin towards the bitter-sweet future awaiting their daughter.

The book’s second half, with Rosa in London, living with Otto’s distant cousin, Gerald Kremer, and Mimi, his wife, feels more like fiction — the stuff of invention — and less like biographical-historical reconstruction. Simons relaxes into the making of a romance between Rosa and Samuel, the Kremers’ son. He moves them to Norfolk to work on the land, thereby producing some of the novel’s most vivid description, as they toil by day in the beet fields, growing closer and much less innocent by night.

Theirs is the novel’s key relationship, though Rosa’s vital connection to her family — sustained here in the reader’s mind by heartbreaking letters sent from Berlin, telling tales of Otto’s and Heinrich’s arrest and detention, with worse to follow — is a source of great misgiving, of latent anger at her being literally outcast, sustaining her sense that her parents chose to do the wrong thing for the best of reasons.

The author embeds this emotional tremor just under the surface of the plot, cleverly peeling back the outer skin of calm at the story’s conclusion to reveal Rosa’s true feelings and to dovetail an earlier plot point into a heady and moving denouement.

The shape of the novel is dictated by the shape of its subject’s life, which gives it a crucial sense of integrity and focus, while also illuminating — though never over-egging — the global nightmare being played out in the concentration camps. It’s a slippery balance to realise, but one which Simons achieves by giving his characters nuanced, complicated, contradictory natures – even the smallest of them – susceptible to circumstance, and mutable. People change in The English German Girl (the title is emblematic of this), with the force of real lives lived, not the force of fiction.