In 2010, Cheuk Hoi secretly travels to Bangkok to conduct a drug operation with his undercover agents in Thailand. As they finish their mission and are about to leave Thailand, an explosion causes all of Michael's undercover agents to die in a sea of fire. At the same time, Michael's good friend, CIB Inspector Eddie Cheung, is killed for unknown reasons, leaving Michael in charge of a female cop who is not yet officially an undercover. Michael knows that Eddie still has undercover agents whose identities have been deleted. To learn the truth about Eddie's death, Michael must find all of the undercovers. He and Priscilla begin to search for the undercover agents.