Zhang a middle aged man struggling with a dead end job as an insurance sales person, on the verge of divorce with his wife, losing custody of her daughter and on top of all this he had to take care of his father who's suffering Alzheimer's. Unknowingly Zhang was invited to join an underground fighting game for financial purposes but eventually Zhang becomes hooked on the fights and turns professional.
Detective Inspector John Rebus is a hard drinking, unkempt, womanizing police officer whose job is his whole life. He is the most senior and most experienced DI at his station. He has a mysterious past that his partner DS Siobhan Clarke learns about from time to time through various comments Rebus makes. She is a young woman who wants to succeed, but does not have much of a personal life. She feels being paired with Rebus jeopardizes her career because of his unorthodox methods, but she is also fascinated by the man and is extremely loyal. DI Rebus' boss is Chief Superintendent Templar, a woman who was one of Rebus' lovers in a distant past. Their relationship is now one where they barely tolerate each other.