Disappearing Isle — Amelia Atwater-Rhodes

Seventeen-year-old Tony Rossi has a pretty good thing going for him: family, home, an okay part-time job, and a tidy future that involves graduating high school and hopefully getting a minor scholarship to a state university. Even his fourteen-year-old sister Kelsey isn't too annoying (though it wouldn't do to admit that to her face). Life is good--until a single winter night sees Tony and Kelsey launched into the middle of a conflict between warring factions of a dying species. The Empress is dead, and the white towers of Ahnmik have fallen. Some who survived the fall desperately scramble to find a way to put their world back together, while others seek to destroy all that remains. Caught between the two sides, Tony needs to discover who he is and what his place is before the conflict destroys him. And no matter what magical forces try to dissuade her, Kelsey isn't about to let her brother fight fate alone.