It's called The Emperor's Code
The 8th book in The 39 Clues series is titled "The Emperor's Code" by Gordon Korman.
The Emperor's Code.
the emperor's code
There is not going to be a 12th 39 Clues book, but there is going to be a new 39 Clues series. The first book in the new series is called The Medusa Plot by Gordon Korman.
Into The Gauntlet
It is called the Emperors Code
It is called The Black Circle.
Beyond The Grave.
Storm Warning
Storm Warning.
Vespers Rising.
The 8th book in the series, The Emperor's Code, was released on April 6, 2010.