A letter arrives in the mail from a woman claiming to have psychic abilities. She warns you of danger but promises good fortune — if you send her money. This is the setup for one of the longest-running scams in U.S. history. These predatory letters were sent to millions of Americans and raked in over $200 million. At the center of it all is the elusive French psychic Maria Duval. Who is Maria Duval, and is she really the mastermind of this fraud scheme? Or has she unknowingly lent a face and a name to one of the biggest cons in history?