Clockwork Angel is the first installment of The Infernal Devices trilogy by Cassandra Clare. After the death of her aunt, Tessa Gray is sent a ticket to travel to London by her brother Nathaniel. On arrival, she is kidnapped and abused by two cruel sisters (Mrs. Black and Mrs. Dark) who work under the name of ‘The Dark Sisters’, until her eventual saving by a group of people who are referred to as Shadowhunters. The rest of the book is based around her discovering the Shadow world and making a life with the new people she encounters.