Wings of Fire: Dark Secret (Book 4) by Tui T Sutherland
The seven dragon tribes have been at war for generations, locked in an endless battle over an ancient, lost treasure. A secret movement called the Talons of Peace is determined to bring an end to the fighting, with the help of a prophecy a foretelling that calls for great sacrifice.
Five dragonets are collected to fulfil the prophecy, raised in a hidden cave and enlisted against their will to end the terrible war. But not every dragonet wants a destiny. And when the select five escape their underground captors to look for their original homes, what has been unleashed on the dragon world may be far more than the revolutionary planners intended…