The 39 Clues: Unstoppable is the third series of The 39 Clues. It was created and announced by Jude Watson. The logo has been changed from red to green, and it is said that Amy and Dan will face their "biggest enemy yet," J. Rutherford Pierce. The series was announced on the Message Board by Jude Watson. It was released October 2013.
Jude Watson said in an interview that they were doing it for the agents of the Message Board as "many kids were upset about Cahills vs. Vespers ending."