1. Chapter I

From ancient footprints to mysterious earthworks, Graham continues his journey into the past alongside experts and curious minds, including Keanu Reeves.

3. Chapter III

Accompanied by local experts, Graham compares ancient oral traditions and learns Sacsayhuamán in Peru may be older than archaeologists ever imagined.

4. Chapter IV

Graham learns of a stone-shaping technique now lost to history, and explores how ancient Amazonians managed to thrive in an inhospitable rainforest.

5. Chapter V

Although thousands of miles apart, Graham considers the possible link between the shamanistic use of ayahuasca in the Amazon and tobacco in New Mexico.

6. Chapter VI

At Mexico's Temple of the Sun, Graham experiences the extent of the Mayans' astronomical expertise and investigates their complex calendar system.