Beginning ten months after the climatic murder of Yan (Leung) at the end of Infernal Affairs, Ming (Lau) finds himself relegated to a desk job as he begins to suspect that a new officer might be another mole. At the same time, Yan is seen in flashbacks as his life of crime escalates and he is assigned to kill his new partner. Moving between events prior to and after Infernal Affairs, Infernal Affairs 3 covers the relationship between the central characters and the gradual loss of Ming