East meets West; past meets present; criminal minds meet skilled artists - welcome to the Mysterium, a circus with dark and thrilling secrets at its heart. Twelve-year-old Danny Woo is half-Chinese, half-British.

His parents are performers in the Mysterium. Following their death in a mysterious fire, Danny is sent to live with his aunt Laura, an investigative journalist. When Danny's school is closed after an explosion, he joins Laura on a trip to Hong Kong.

She is researching the Triad gangs; he is trying to understand more about his cultural background. But Laura disappears, and Danny is plunged into a dangerous quest to find her - which opens the door on the past he could never have imagined, and which leads him to question everything he has ever known about his past.