Shades of Truth (2004)

After a slight injury on the head, Dung Chung Cho gains his past memories as Wu Song 900 years ago and tries to convince TC that he is his long lost brother Lin Chong. Meanwhile, one of Sung Po's men, Kwan Lo (Derek Kwok) begins to suspect Dung Chung Cho as an undercover for the police and is also plotting to overthrow Sung Po's position in the gang. How come the police can never gather enough information to capture the triads for holding illegal businesses and charge them for attempting to murder so many people? It is then when Dung Chung Cho begins to realize that there is also an undercover in the police force working for the triads.