Here's what we know:
* Early attempts: In 2009, shortly after the book series' launch, there were talks of a movie adaptation, with DreamWorks Pictures expressing interest.
* 2011: A failed pilot: A TV pilot was filmed for a potential TV series, but it was ultimately not picked up by any network.
* Ongoing Interest: The series' popularity continues, and there are still rumors and hopeful fans who believe a movie or TV series could still happen someday.
While a movie adaptation hasn't materialized yet, you can still experience the adventure of "The 39 Clues" through the books, the online game, and other related media.