Incarceron by Catherine Fisher 
442 pages.

To free herself from an upcoming arranged marriage, Claudia, the daughter of the Warden of Incarceron, a futuristic prison with a mind of its own, decides to help a young prisoner escape.

Read about Catherine Fisher and her ideas that inspired Incarceron.

Sam’s review:
Advanced technology meets medieval mentality in this thrilling story. Finn, 17, is a prisoner in the mysterious and rough world of Incarceron. Though this prison is a closed system and all its residents have been born there, Finn has vague memories of a life “Outside.” He also has a tiny tattoo that seems to have some significance. When a woman that he has captured recognizes the tattoo and reveals a crystal key, Finn becomes obsessed with the need to discover his origins. Meanwhile, beautiful and headstrong Claudia, daughter of the Warden of Incarceron is unhappily betrothed to Caspar, the spoiled heir of the Realm, a world that is trapped in the 18th century. Claudia was originally destined to marry Giles, who was killed in an accident when he was young. She believes that he is still alive and is obsessed with finding him. The stories of Finn and Claudia are riveting, and the plot takes many surprising twists as their stories come together. Incarceron is a fully successful combination of good characters, engrossing world-building, and a fast-paced storyline. Even the nature of Incarceron itself is a captivating mystery.