The Phantom of the East Tower — Ellen Alexander

Emma's excitement for freshman year quickly wanes when she discovers Doug has a new girlfriend. Although heartbroken, she's determined to throw herself into school activities, and she decides to go out for cheerleading. When she begins to witness strange encounters and glimpses what appears to be a phantom on the castle's east tower, Emma's investigative skills are put to the test and sparks a secret adventure through the academy's underground caverns. When an unforeseen danger threatens to undo all that she's accomplished, Emma must gather her courage and do the right thing. But what will it cost? And will she and Doug ever be the same again?