Sally Lockhart is sixteen years old and incredibly pretty. Her knowledge of literature, languages and music leaves much to be desired, but she knows how to run a business, ride a horse and shoot a pistol without missing a beat. When her father dies under mysterious circumstances, Sally is left alone. She is in danger, although she doesn't know it. And now her life depends on solving a dark mystery. Having revealed the secret of the Maharaja's ruby, Sally changed her destiny and found new friends. However, a few years later, the brave girl and her friends will have to become detectives again. The random events that happened to each of them turn out to be links in one chain. And behind all this is the all-powerful owner of the Polar Star company and the creator of deadly weapons. With every step, Sally, Jim and Fred are drawn deeper into the ominous shadow of the North Star.