Minos

Minos, the third and final book in the Corey Logan Trilogy. 
The title derives from the mythical king of Crete who every lunar year condemns seven Athenian youths and seven maidens to be eaten by the ferocious Minotaur. Minos begins at the Olympic Academy, where Billy's friend Sara has just carved a magic circle in the hardwood bathroom floor with an ancient double-edged dagger. She twirls inside her circle calling on the Oracle of Apollo to help her find a modern-day Theseus, the reincarnation of Athens' “hero of all heroes” who slew the Minotaur. 

Lost in her magical dance, she knocks over a candle, sets fire to the curtains, and is suspended from school. She is sent to Abe for treatment. Abe discovers that Sara has patched together an entire mythological universe and language with which she tries to make him see that lives are at stake. It is not easy to convince the authorities. But Corey knows that young people are indeed being murdered, and soon Sara's dire warnings begin to make sense. But who is the modern-day descendant of Minos? The key is inside Sara's head.