NEW YORK (AP) — As book gimmicks go, this one has a heart of gold.

Make that a pot of gold.

A new young-adult trilogy to launch in October with “Endgame: The Calling” is at the center of an interactive project that includes a puzzle that leads to a key that leads — at least for one lucky person — to $500,000 in gold coins.

The subsequent two books will have progressively larger payouts, and all will require the use of a website that has not yet gone live, publisher HarperCollins said.

The project also includes YouTube videos, gaming designed by Google’s Niantic Labs and social media. Twentieth Century Fox has acquired film rights.

James Frey, the author of the discredited memoir “A Million Little Pieces,” and his production company, Full Fathom Five, will turn out nine novellas in addition to the three books. The first book is co-authored by Nils Johnson-Shelton.

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