D.I.D. 12 Episode 20

Ding Lok Fung and Lin Yuk Sui clash while Ying Hoi manages to break free and locate the prisoners. At that moment, Ying Hoi’s dark personality takes control and attempts to kill them. Yeung Tsz Fei arrives and desperately tries to stop him, but is suddenly stabbed during the struggle. Both Ying Hoi and Tsz Fei are hospitalized. While recovering, Ying Hoi’s dark personality reappears and reveals a cruel secret about him to Tsz Fei. After being discharged, Ying Hoi plans to visit someone connected to his past in hopes of letting go of old grudges. However, when Tsz Fei arrives, she realizes the person before her is not Ying Hoi—but his dark personality. (Source: Chinese = TVB || Translation = KamilaRN at MyDramaList)