The Percy Jackson Countdown Day Four: The 39 Clues

The 39 Clues series was started by and is overseen by Rick Riordan, author of the Percy Jackson and the Olympians series. However, each book has a different author (though some authors write more than one title in the series). Each book has clues to the mystery, and you can also play the game on an interactive website (www.the39clues.com).

"What would happen if you discovered that your family was one of the most powerful in human history? What if you were told that the source of the family's power was hidden around the world, in the form of 39 Clues? What if you were given a choice — take a million dollars and walk away...or get the first Clue? If you're Amy and Dan Cahill, you take the Clue — and begin a very dangerous race." (from publisher's description)

The 39 Clues series
Book 1: The Maze of Bones by Rick Riordan
Book 2: One False Note by Gordon Korman
Book 3: The Sword Thief by Peter Lerangis
Book 4: Beyond the Grave by Jude Watson
Book 5: The Black Circle by Patrick Carman
Book 6: In Too Deep by Jude Watson
Book 7: The Viper's Nest by Peter Lerangis
Book 8: TBA (by Gordon Korman & due out April 2010)
Book 9: TBA (by Linda Sue Park & due out May 2010)
Book 10: TBA (by Margaret Peterson Haddix & due out August 2010 - also the last book in the series)