Clockwork Prince is a novel written by Cassandra Clare. It is the second novel in the Infernal Devices trilogy and is written through the perspective of the protagonist, Tessa Gray, who lives at the London Institute among Shadowhunters, a group of half-angel-half-human beings called Nephilim. After the recent failings of Charlotte, the manager of the Institute, the Council of Shadowhunters begin to question her ability to lead. Now Tessa and her friends must find Mortmain – an evil industrialist bent on destroying all the Nephilim in the world - or risk losing control of the Institute.