After graduating at the top of her class from the police academy, 27-year-old Iris joins a police station in the south of France. Upon arriving at this brigade of colorful police officers, she receives a less than warm welcome. Her in-depth knowledge of the law and her insistence on following the rules do not sit well with everyone, particularly Victor, 54, her designated partner, a lone wolf cop whose methods are considered outdated. Despite their differences in age and background, when Iris and Victor are assigned a case that seems almost closed in advance, by combining their talents, they discover that it is not a simple traffic accident but a premeditated crime. While their success brings the duo closer together, Victor quickly discovers that Iris is not just anyone's daughter... What secret from the past threatens to resurface?

Following the inexplicable sinking of a trawler and its fishermen who remain untraceable, Abigail, an oceanographer, is sent by IFREMER on a mission to Fécamp, her hometown, which she left a few years earlier following a family tragedy.