Clockwork Angel, the first book in the Infernal Devices series by Cassandra Clare, is set in Victorian London and follows Tessa Gray, a young girl who travels from America to find her brother. Upon her arrival, she discovers she has the ability to transform into other people, a power coveted by dark forces. Tessa soon finds herself caught in the world of Shadowhunters, who are dedicated to fighting demons and protecting humanity. As Tessa learns about her powers and the Shadowhunter world, she meets Will Herondale and Jem Carstairs, two young Shadowhunters with a deep bond. They face various challenges including a mysterious villain known as the Magister, who seeks to harness Tessa's abilities. Throughout the story, themes of friendship, love, and sacrifice emerge as the characters confront their own inner demons and the dangers around them. The book combines elements of fantasy, romance, and adventure, drawing readers into a richly crafted world filled with intriguing characters and complex relationships. Clockwork Angel sets the stage for Tessa's journey of self-discovery and her fight against malevolent forces, making it a compelling read for fans of young adult literature.