"Sapphique" is a young adult fantasy novel written by Catherine Fisher. It is the sequel to her first book, Incarceron, and continues the story of the characters trapped in a vast, living prison. The narrative explores themes of freedom, identity, and the struggle against oppressive systems. The plot follows Finn and Claudia as they navigate the challenges of their world, seeking to escape the confines of Incarceron and uncover the truth about their identities. The novel combines elements of adventure and mystery, appealing to readers who enjoy intricate world-building and character development.