The Chronicles of Leënde 

Facing a political marriage with a much older man, fifteen-year-old aristocrat Julia Schreiber convinces her father Victor—a commanding knight and beloved hero—to first take her on a journey to Leënde, a magical land whose people are dying from a mysterious illness. There she meets Tristan, a beautiful but aloof archer who seems to be keeping some secrets of his own. All too soon, however, dark machinations threaten to upend this idyllic adventure and throw Julia into a fight beyond her wildest dreams…