The worthy French film “Sarah’s Key” has two overriding aims, like the 2007 novel by Tatiana de Rosnay from which it is adapted.

The first is to expose a generally unknown — or willfully forgotten — chapter in France’s long, blemished relationship with its Jewish population.

The other is to connect the Holocaust to the present in a way that makes it come alive for contemporary audiences who are, inevitably, a couple of generations and thousands of miles removed.

To that end, the film shifts back and forth between Sarah, a Jewish child in Paris in 1942, and Julia, an American journalist (played by Kristin Scott Thomas) in Paris 60 years later. One storyline, however, proves immeasurably more compelling than the other.

Frankly, it’s gratifying to report that the Holocaust-era saga is the primary reason to see “Sarah’s Key.” The riveting (albeit fictional) wartime events deliver a knockout emotional punch while the present-day story dissolves into half-hearted melodrama and half-baked contrivance.

Melusine Mayance plays a 10-year-old whose family is torn asunder in 1942 Paris. photo/julien bonet/courtesy of the weinstein company

On balance, though, the good far outweighs the hokum. 

“Sarah’s Key” will be screened only once in the San Francisco Jewish Film Festival: on Saturday, July 30, when it serves as the opening night film for the Berkeley portion of the festival. The 108-minute film, in French and English, will open in theaters Aug. 5.

At its core, “Sarah’s Key” wants to engage us in profound moral questions of responsibility and behavior. The most uncomfortable probes would seem to be directed at non-Jews, but the notion of passive participation in injustice, persecution and murder is surely relevant to anyone.

In 1942, the Paris police arrested thousands of Jews and confined them for several frightening days in the Velodrome d’Hiver, an indoor stadium, before shipping them to Auschwitz. (This despicable “Vel d’Hiv” episode is the subject of “The Roundup” and a crucial part of the subtext of “The Names of Love,” both in this year’s festival lineup.)

“Sarah’s Key” tells the story of Sarah and her parents, who were among the arrestees. The quick-thinking girl concealed her little brother in their apartment before the gendarmes hustled them away.

Once it dawns on Sarah that her brother’s fate is in her hands, she embarks on a daunting mission that compels her to depend on the kindness of strangers.

Now, it should be noted that some neighbors lobbed anti-Semitic insults as Jews were taken from their homes, while others took action (for or against) on the basis of mercenary self-interest.

It is the latter possibility that chills Julia, a Paris-based American researching a magazine story commemorating the 60th anniversary of the roundup. Played by Scott Thomas, working in French and English, Julia incredibly discovers that the apartment she and her French husband are redecorating, and which his family has long owned, belonged to Sarah’s family.

Did Julia’s in-laws accidentally benefit from the expulsion of Jews? Or, horrible as it is to contemplate, were they abettors and collaborators, propelled by hatred or opportunism?

This is a mystery fraught with consequences, no doubt about it. But once the secret is revealed, Julia’s life devolves into prosaic melodrama.

The usually remarkable Scott Thomas gives a pedestrian, unmemorable performance, but it can’t be laid entirely at her feet. It’s unavoidable that the stuff of Julia’s life — a self-absorbed husband, an unexpected pregnancy — would seem trivial next to the life-and-death dangers, traumas and sorrows that buffet Sarah.  

Ultimately “Sarah’s Key” has a third goal, to leave viewers mulling what we would do if our neighbors were hauled away. Would we conceal and shelter the innocent (at great personal risk) or would we benefit from the spoils?

It’s a useful question but not one that will occupy most Jewish viewers — who, after all, will identify with Sarah and her parents more than Julia’s in-laws.

It is that personal connection, across the years and miles, that makes “Sarah’s Key” a moving and worthwhile addition to the filmography of the Holocaust.

“Sarah’s Key” screens at 7 p.m. Saturday, July 30, at the Roda Theater in Berkeley; followed by Berkeley opening-night reception. $22-$25. Opens Aug. 5 at the Embarcadero Center Cinema in San Francisco and Aug. 12 at the Albany Twin in Albany.