Archaeologists investigate the discovery of more than 100 ancient skeletons buried in a hillside outside Mexico City. They also attempt to decode the secrets of a mysterious ancient manuscript to reveal the secrets of Aztec ritual sacrifice, and finally manage to complete their groundbreaking experiment to build a replica Aztec pyramid.

Archaeologists unearth the remains of the ancient civilisation from beneath Mexico City, digging deeper than ever before to find out who the Aztecs were and how they built their remarkable empire. The first episode features an attempt to build a replica of a pyramid, as well as investigating the mysterious pyramid ruins being unearthed in the heart of Mexico City and a journey into a set of underground tunnels that have lain undisturbed for centuries.