Two Spanish Egyptologists, Sonia Gonzalez and David Donnelly, find during an archaeological excavation in the tomb of an Egyptian priest some strange inscriptions that turn out to be a fragment of the Critias, Plato's dialogue that tells the story of Atlantis. Surprised by the discovery, they embark on an investigation into the origins and significance of their discovery in which they will soon have the help of a mysterious character who will guide their steps. With the help of a friend and colleague from the university, Alvaro de Andrade, they travel to the Brazilian city of Manaus, in the middle of the Amazon rainforest, where they make contact with a retired police inspector who puts them on the trail of a strange city lost in the jungle in which the key to the Critias, the inscriptions on the Egyptian tomb and the existence of a civilization that disappeared in the night of time may have been the common origin of the great human civilizations of the Ancient Age. Guided by a strange character, and closely pursued by a cruel mercenary in the pay of a mysterious international lobby that intends to appropriate at all costs its possible discoveries, the protagonists of the novel embark on an initiatory journey that will change their lives, put them in touch with the true past of humanity and make them messengers of a change in which the last hope of humanity can be found.