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. As her research progresses, new mysterious phenomena occur at sea, making the activity of fishermen, although essential to local life, impossible. Abigail will learn that these disasters could originate from an underwater presence capable of upsetting the fragile balance between man and nature... What if the cause of the disturbances does not correspond to anything known?