It’s 11 years since Suite Française, Irène Némirovsky’s novel about France under German occupation, became a literary sensation. Critics called it a masterpiece. The New York Times ranked it with the “greatest, most humane and incisive fiction” of the second world war.The surprising thing is that it has taken so long to come to the screen – but the film, directed by Saul Dibb and starring Kristin Scott Thomas and Michelle Williams, was worth waiting for. It’s both faithful to the book and a clever distillation of its sprawling narrative, pared down to a touching and believable story.

Némirovsky was 39, with many successful books behind her, when, in 1941, she started work on a novel she envisaged as a symphony, but of five parts, modelled on Beethoven’s Fifth. In the increasingly antisemitic 1930s, her family converted to Catholicism. With the arrival of the Germans, they went into hiding. Even so, she had a premonition that time was running out for France’s Jews. “Just let it be over,” she wrote in her diary, “one way or another.” By July 1942 she had written the first two parts of her novel, “Storm” and “Dolce”, and an outline of the third, Captivity, when the French police came for her. She died a month later in Auschwitz of typhus.

But her two daughters survived, and preserved her notebooks, not knowing what they contained. It was only in the 1990s, having decided to donate them to an archive, but to transcribe them first, that Denise, the elder, discovered the novel. There were also “Notes on the State of France”, in which Némirovsky railed at the cowardice of the collaborators.

The most memorable part of Suite Française – movingly rendered in the film – was its depiction of the great exode, when 6 to 8 million people took to the roads to escape the advancing Germans, in a river of cars, bikes, carts and prams. The flight was well known to historians, though it had never been portrayed with such passion. But it’s “Dolce” and events in the outline of “Captivity” that form the heart of this excellent film: the touching relationship between an unhappy young French woman and the German officer billeted with her family, with all its ambiguous, troubling echoes of collaboration. Némirovsky was a superb storyteller, and the film has done her justice.

• Suite Française is out on general release.