Poseidon's Academy and the Vanishing Students, Paperback

With the nereids banished from Poseidon's Academy, Hailey expects her third year of high school to finally be normal--no monsters trying to eat her, no incurable disease sweeping through the Academy, and no one trying to resurrect the gods. But the Fates have different plans in mind for Hailey.

Only a few weeks into the school year a student vanishes. Everyone believes them lost in the palace, but when more students begin disappearing one by one, Hailey realises someone, or something, is taking the students and that everyone living in the Academy is in serious danger.