The trawler Marie-Morgane sinks suddenly and inexplicably with all its crew, including Captain Lenormand and his son. When Nolwenn Lenormand hears the news she's convinced that a submarine on maneuvers must have been responsible.
A police captain specialized in Crime History is investigating on the discovery of a corpse found on the beach of Saint-Malo. She tries to convince her temporary teammate that their case would be linked to piracy.
