Carved into the Peruvian desert thousands of years ago, the Nazca Lines have puzzled archaeologists and laypeople alike ever since their discovery 100 years ago. Stretching over hundreds of square miles, thousands of geometric shapes and animal figures mark the desert landscape - some as big as football fields, but all flat as the land itself, making them virtually invisible from the ground. Theories to explain the lines range from giant maps of the stars to alien runways to places for elaborate and bizarre rituals. Why would a people who couldn't fly have built images that could only be seen from the air? Olly travels to ancient cemeteries and Nazcan cities curiously off-limits to camera crews. He explores underground tunnels used in psychedelic cult initiations and tries to venture into the spirit world himself to unravel the mystery of the Nazca Lines.