A book containing clues leading to jewels worth £1 million (US$1.76 million) looks set to spark an international treasure-hunt.
Secrets of the Alchemist Dar, by millionaire author Michael Stadther, will incorporate riddles leading to 100 gems hidden around the world.
A single jewel described as "one of the most precious stones on earth" is worth £530,000. Claiming that someone in one country has the same chance of finding them as someone on the other side of the world, Stadther is secretive about what form the hunt will take.
"It might be physical; it might not. People might have to get in cars or on planes; they might not," he said.
But he did give one hint: "I have found the power of the Internet -- it's vast."
In 2004, Stadther published A Treasure's Trove in America, sending thousands of "trovers" looking for 18-carat gold coins that he and his wife had scattered around state parks across the country.
The coins, hidden in the bark of trees or under debris, were redeemable for jewelry encrusted with diamonds, rubies and emeralds, all based on the story's animal characters.
Jason Davis, a student in cognitive neuroscience, borrowed money for a two-day bus journey from California to Foss State Park in Oklahoma to retrieve a coin that he later redeemed for jewels worth US$250,000.
Inspiration for the book came from the artist Kit Williams's Masquerade, which sold more than 1 million copies.
Secrets of the Alchemist Dar is due for international release in September.