Eighteen months ago. Chinatown, London. A police raid goes disastrously wrong. People die. Today, the police officers involved in the swoop are dead. Serial, Purple One Five, are all dead, except the serial commander – Sergeant Brian Gibson. In Hong Kong, a woman’s body is discovered in a seedy downtown Wan Chai hotel. Detective Inspector of Police Mandy Lee must determine who she is and who killed her. Lee identifies the woman as Andrea Ventress-Gibson. Lee’s investigation leads her to the UK, but Andrea’s new husband, Sergeant Brian Gibson, is missing – whereabouts unknown. Meanwhile, in the UK, Road Policing Officer PC Ed Roberts discovers a cyber-attack on a police database. But he’s ordered to chaperone D. I. Lee. As a team they soon find that their enquiries are linked. Against orders, Roberts follows Lee to London’s Chinatown, where they come into direct conflict with a Hong Kong underworld organisation - Crimson Dragon. And confirms Lee’s suspicions her estranged step-brother is involved. Can Lee and Roberts discover Gibson’s whereabouts and stop Crimson Dragon?