During a dive in the crystal-clear waters off the Andalusian coast, Commissioner Rubén de Freitas discovers documents that have been well sealed on the seabed for over four hundred and fifty years. He discusses this with a professor from the University of Granada, but just a few days later, she is dead. Then, Rubén's apartment is broken into and searched—could there be a connection to his seemingly insignificant find? Rubén has no idea of the danger he is in, as someone is on the hunt for him...