London, 1854: Castor is discovered locked away in a basement. He has been there for five years, but he hasn’t been alone. The Family has kept him company. These are his multiple personalities that have emerged out of the dark. Mr Pickwick is the father figure with a habit of quoting from the Bible. Miss Trent is the nervous governess who dreads germs. Skinner is the street urchin with a smart answer for everything. The Infant Prodigy is a cranky genius. Together, this most unusual team of detectives tries to solve the mystery of why Castor was imprisoned. The clues lead them to the most fabulous jewel in the world – the Koh-i-Noor. The young Maharaja Duleep Singh has just arrived in England to present the diamond to Queen Victoria. Hunted by the deadly Blue Turbans, Castor and the Family race against time to unravel the connection between the diamond, his imprisonment and the disappearance of his parents.