Luminous

"Liora has spent her life in hiding, knowing discovery could mean falling prey to the king's warlock, Darius, who uses mages' magic to grow his own power. But, Darius doesn't take her. Instead, he demands that her younger sister return to the capital with him. To make matters worse, Evran, Liora's childhood friend and the only one who knows her secret, goes missing. To find Evran and to save her sister, Liora must embrace the power she has always feared"--Provided by publisher.