Skyshade

"Back in Grim's castle on Nightshade, Isla is reeling in the wake of a brutal battle and the devastating truths it exposed. Her future--and the fate of the world--now hinge on a heart split in two. Past Isla, who fell in love with the ruler of Nightshade, fights to resist feelings she considers treasonous. The Isla of the present, who has seen the ruin her powers can cause, will do anything to save Lightlark and its king"--