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 life with the new people and world she encounters.