Circle of fire - Michelle Zink

With time dwindling but her will to end the Prophecy stronger than ever, Lia sets out on a journey to find the remaining keys, locate the missing pages of the Prophecy, and convince her sister Alice to help--or risk her life trying. Lia has her beloved Dimitri by her side, but Alice has James, the man who once loved her sister--and maybe still does. James doesn't know the truth about either sister, or the prophecy that divides them. And Alice intends to keep it that way.

There are some secrets sisters aren't meant to share. Because when they do, it destroys them.