The Labyrinth Queen by Tansey Morgan

In a world where Kings and Queens make court, where monsters are real, and magic is to be feared, there exists a great and terrible labyrinth of unknown origin, lorded over by an equally enigmatic and mysterious King. No one who enters the labyrinth without the King’s permission leaves, those who defy the King are thrown in as punishment, but for everyone else who lives within this King’s domain, the labyrinth is a source of safety and protection. For Cailyn, the labyrinth is about to become a nightmare from which she can never awaken.