BARCELONA — Gilles Paquet-Brenner’s “Sarah’s Key,” toplining Kristin Scott Thomas, will close the 58th San Sebastian Film Festival.

Based on Tatiana de Rosnay’s bestseller, “Sarah” turns on an American journalist living in Paris. While she is researching the World War II Vel d’Hiv roundup of Parisian Jews by the French police, she stumbles on a terrible secret.

Helmer Paquet-Brenner (“Gomez and Tavares,” “Les Jolies choses”) co-penned the script with Serge Joncour. “Sarah” is produced by Paris-based Hugo Prods., and international sales are handled by France’s Kinology.

In a further announcement made Friday, the festival organization confirmed that actress Olivia Williams will accept a Fipresci Gran Prix at the opening ceremony, representing Roman Polanski’s “The Ghost Writer.”

Helmers Hans Petter Moland and Sebastian Cordero will preside over the New Directors and Horizontes Latinos sidebar juries respectively. The main competition jury will be unveiled shortly.

“Sarah” will world preem at the upcoming Toronto Film Fest. Pic is included in its Gala line up.

San Sebastian runs Sept. 17-25.