In 1925, British explorer Colonel Percy Fawcett, along with his son and another companion, disappeared while searching in Brazil for the Lost City of Z.

Not long after, Peter Fleming, who was literary editor for London's The Times, answered a small ad seeking volunteers for an expedition to find out what had happened to them.

They left everything up to the leader they hired, an eccentric American, Major George Lewy Pingle (not his real name) who lived in Brazil.

Major Pingle, whose bizarre moments of unreason had been making things more and more difficult all along, claimed the search was impossible and he was giving it up.

So the two groups furiously raced each other down the long Tocantins and Amazon rivers to the port city of Para, where they could report back to England and catch a ship for home.