A tycoon, Man is murdered. His son Fung is determined to find out who did it. Who is the real killer in this mysterious case? The night when Man was killed, Shan, who has been working in his company for years, found out that she is his illegitimate daughter. She worries that she may have killed Man while sleepwalking. Meanwhile, Fung and Shan find out that Man was behaving abnormally that night and wanted to rape Fung's cousin, Tung. Tung, who has congenitally impaired hearing, is suspected of killing Man out of self-defence.