Parisian archivist Hélène knows very little about her mother, Nathalie, who died when she was four. In the hope of learning more, she places a newspaper advert calling for information on Nathalie and two unknown men pictured with her at a tennis tournament in 1971. Against the odds, she receives a response from Stéphane, a Swiss biologist: his father is one of the people in the photo. More letters, and more photos, pass between them, in an attempt to unearth the truth their parents kept from them. But as they piece together events from the past, will they discover more than they can actually deal with? Winner of twenty-five literary awards, this dark yet moving drama deftly explores the themes of blame and forgiveness, identity and love.