Adventurer Niall McCann tracks the final journey of British explorer Percy Fawcett, who disappeared in 1925 with his son Jack and Jack's friend Raleigh Rimmell when the trio entered the Amazon jungle in search of an ancient lost city he called "Z." Among the clues McCann has to work with: Fawcett's signet ring, which surfaced 60 years after his disappearance, and a map that only his wife could read. Also: evidence that the Amazon supported large populations in the pre-Columbus era.