At yesterday’s Random House preview I learned that there is one final book coming out in the series: The Diamond of Darkhold. The publication date is September 9, 2008. According to the flap copy, in Sparks Lina and Doon find a beat-up book missing most of its pages, but in it is mention of a device that may still be in Ember. So they go back to find it. Haven’t read it yet, but it sounds as if Jeanne DuPrau has penned a compelling and intriguing end to her series.