Abigail, an oceanologist, is sent by IFREMER on a mission to Fécamp, which she left a few years earlier following a personal tragedy. She must investigate the inexplicable sinking of the Rose Davies, one of her father's trawlers with 14 sailors on board. While she is conducting her research to find the wreck with the gendarme Prigent, mysterious phenomena occur at sea.

Abigail is in shock after Prigent was killed by the explosion of one of the bombs from the First World War that lined the seabed. And Sylvia, his sister-in-law, an environmental activist he had been following, is in a coma. Defying the ban on going out to sea, the scientist returns to the water to understand and record the seismic activity present in the fault off Fécamp.