In the past few years there has been a wave of acclaimed French novels about Vichy and the Holocaust - Irène Némirovsky's Suite Française, Jonathan Littell's The Kindly Ones, Tatiana de Rosnay's Sarah's Key and now Fabrice Humbert's The Origin of Violence, winner of the first-ever French Orange Prize.

Does Humbert's novel live up to the acclaim it has received across the Channel? The historical research is impressive, the storytelling moving and compelling. But this is a top-heavy book, with long, typically French but not very interesting speculations about Evil and History (both with a capital letter), improbably mixed with an inordinate amount of sex. It could comfortably lose 50 pages.

The story is concerned with two looks. The first appears in a photograph. The narrator, a French writer and schoolteacher, leads a school trip to Weimar and Buchenwald. At the latter, he sees a black-and-white photograph in which a prisoner is staring in an unforgettable way at one of the SS men, Erich Wagner.

There is something striking about the prisoner's expression, but what really takes the narrator aback is the uncanny resemblance between the prisoner and his own father, a dark, saturnine figure, born during the war.

The novel is about the narrator's attempt to discover who this man is who so resembles his father, and the mystery of why he ended up at Buchenwald when the narrator's family, the Fabres, a successful and prosperous gentile family from Normandy, survived the war. Indeed, in some cases they prospered during the Vichy years.

The second gaze comes later in the novel. A woman walks into a room. She is young and beautiful. A man stares at her. They exchange looks and immediately fall in love. This moment will have consequences for both of them. Is there a connection between these two moments, these two glances?

This becomes a compelling account of a family history in Vichy France. Humbert has immersed himself in the historical research. The scenes at Buchenwald are powerfully written, with vivid descriptions of the sadism and brutality of monsters like Martin Sommer, Karl and Ilse Koch and Dr Wagner, the SS man from the photograph.

All the way, you expect a twist and eventually you get two - both quite unexpected. The problem is that this is all bogged down by those unnecessary philosophical meanderings. This is a shame because the main plot is gripping and rich enough in fascinating observations on memory and forgetting, post-war justice, and moral judgment.

David Herman is the JC's chief fiction reviewer