While at the port one night, Marina Quiroga, an eligible single woman and sister to the city's police chief, unexpectedly surprises a man who is stabbing a woman. This will awaken within Marina her instinct as a detective, and with the help of her loyal butler Héctor, she will start to investigate the crime.

Marina has been kidnapped by the killer but manages to escape, though in her escape she is badly hurt. With Pablo's help, Héctor discovers the identity of the artist behind the picture of the House of Water, and they decide to seek him out to ask about the killer's identity.

After discovering that the murders began thirty years before in Orense, Marina, Ramírez and Pablo go there to search for clues to the fleur-de-lis killer’s true identity; what they never realised is that all the while the killer has been closer to them than they ever suspected.