In Paris, Lionel Kasdan, a retired police captain, investigates a strange murder: a choirmaster has been found dead in his church, his eardrums shattered, no witnesses. Frank Salek, an Interpol agent who risks being suspended by his superiors because of his excessive behavior, is on the trail of a secret organization that specializes in kidnapping children. When Salek hears about the choirmaster's death, he thinks he's found a link with his own investigation and accepts to team up with Kasdan. But the more the investigation progresses, the more Salek seems to lose his footing, as though caught up by a deeply buried secret. From then on, the two men will plunge into an affair that finds its source in World War Two's darkest hours.