D.I.D. 12 Episode 6

Ding Lok Fung warns three major drug traffickers that they are in danger, forcing them to temporarily stop operations. However, his superior, Ye Pei Lin, disapproves and reassigns the case to Cheung Mun Kwong. Ying Hoi suspects the “New Seven Deadly Sins” killer is not targeting the drug lords, but someone else entirely. With A Yin’s suggestion, he visits Yeung Tsz Fei to discuss the masked girl in the videos. Tsz Fei believes the girl is neither the killer nor the mastermind. It is revealed that the masked girl is actually Tsz Fei’s former student and patient Lee Yan, who later refuses treatment and goes missing. Meanwhile, Lok Fung is attacked by Tang On, but is saved by his old friend Ho Tung—though Lok Fung criticizes him for not changing his ways. (Source: Chinese = TVB || Translation = KamilaRN at MyDramaList)