Archimancy (Shadow School, Bk. 1)

Cordelia Liu knew Shadow School was going to be different. Different she expected, but still, Cordelia can't shake the feeling that something's not right. The answer isn't just right in front of her - it's in her gym, next to the bulletin board, even in the cafeteria. The school grounds are filled with ghosts. The school was create with sinister intentions, and someone is willing to go to extreme lengths to ensure that the ghosts remain trapped forever.