A mysterious well filled with bones reveals a strange practice in ancient Persia... Why were these ancients laid bare atop desert towers, their bodies picked clean by vultures before being consigned to the grave... Thousands of kilometers away, archaeologists digging in Mongolia uncovered a two-thousand-year-old textile that holds the key to solve the mystery of what soma, the mysterious elixir that brings light, gods and immortality, is made from. And, in Sichuan, hanging coffins are discovered... legend has it the ancient Bo People could fly. To date, we still haven't been able to determine how they suspended their leaden coffins from the cliffside. Who were the Bo? How did they achieve this and why did they disappear?