Richard Malinowski (Jean Dujardin) is a workaholic cop who rarely gets to see his 10-year-old daughter. So when she's abducted and murdered, his grief and guilt are all-consuming. His colleagues make the case their top priority and swiftly arrest Daniel Eckmann (Laurent Lucas). Eckmann begins writing Malinowski from prison, claiming his innocence and offering exonerating evidence. The two must work together to try and catch the real killer and make sure justice is served.