Marina, An eligible single woman and sister to the city's police chief unexpectedly surprises a man who is stabbing a woman. Marina and her instinct as a detective with the help of loyal butler Hector will start to investigate the crime.
After detaining a suspect, Marina and Castaño realize the real killer is still free. The police plan to host a masked party at the House of Water to lure and catch the murderer.
Marina and Castaño reopen a case after detaining a killer. They suspect the real killer is still loose. Cops plan to catch him by hosting a masked party as a trap for clients of the House of Water.
Marina escapes her kidnapper but is injured. Héctor and Pablo identify artist behind House of Water painting, seeking him to uncover killer's identity.
Marina must rescue Margo before the killer strikes. As she gains Margo's trust, the masked killer appears. Marina saves Margo, promising protection. But she soon learns that everyone's true motives are hidden, and she can't trust anyone.
Marina finds the killer's mask in Pablo's car and a fight with the cop ensues, until they lose control of the car and crash; a couple of days later she wakes up in her bed.
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.