The discovery and study of Ciudad Perdida, an ancient city in the Colombian jungle. Archaeologist Peterot guides viewers through the history of this Tairona civilisation, rediscovered in 1976 by Luisa Fernanda Herrera.

The story explores the challenges of exploration, the social and political organisation of the Tairona, highlighting their advanced construction and communication techniques.

Finally, the episode reveals the disappointment of the Spanish, attracted by gold but deceived by the tumbaga alloy used by the Tairona, and the tragic end of the civilisation due to disease.