For Cressida Quillionette, Cinderbloom Academy is everything she could never have. A gateway of possibilities. But to attend the secluded academy means she can never go back home.
When she is finally admitted to the Head School, she discovers that this small-town clockmaker's daughter is to be transformed into a genteel young sorcerer. She is even put into a room with her best friends, including Miles, her secret sweetheart.
But all isn't what she expected. Discussing classes with other students is prohibited, and all gained knowledge is kept locked behind a blood oath. Soon, the strictures cut her off from her friends. Miles suffers mysterious injuries he won't talk about, Cressida isn't sure what she helps assemble in her workshop, and there are gasps in the hall about a student's death.
Until now, she thought the rules and secrecy were all for the best, but something dark seems to lurk beneath the surface. There are too many signs to ignore. When the enigmatic Headmaster pulls her aside for specialized instruction, she is submitted to an experimental ritual that changes her indelibly.
Now she finds herself cornered by the question: what is the change the Headmaster wishes his students to effect on the world? Is losing her humanity worth it?
And when the time comes to fight back with her fellow students, will she?