Clockwork Angel by Cassandra Clare is the first book in The Infernal Devices trilogy, a prequel to The Mortal Instruments series. Set in Victorian London, it follows Tessa Gray, a young woman who discovers she has magical abilities after her brother is kidnapped. She is drawn into the world of Shadowhunters, a secret group dedicated to protecting humanity from demons and other dark forces. Tessa becomes entangled in a battle between rival factions, all while grappling with her own identity and powers. The novel explores themes of love, loyalty, and the clash between good and evil, all set against a richly detailed historical backdrop.