In 1826, William Morgan, who lived in Batavia, New York, advertised that he was writing a book that would expose the secrets of the Freemasons. And then he vanished.
Research:

Percy Fawcett, Manuscript 512, and a Lost City in the Amazon, Pt. 2
37:10

Percy Fawcett, Manuscript 512, and a Lost City in the Amazon, Pt. 1
34:05

SYMHC Classics: Swill Milk
39:22