During a school visit to the Experimental Archaeology Center (CAREX), some children find the body of a young girl in the place where a replica of a Neanderthal burial site should be. The young girl is Eva Santos, from the nearby town of Atapuerca, and she is dead. Her body is naked and placed in a fetal position. A gruesome ritual crime reminiscent of another that occurred six years ago in the same area. Has the “killer of the site”, who managed to escape six years ago, returned?