Hong Kong police agent Cheung (by Aaron Kwok) works undercover in Kang’s (by Sean Lau) drug cartel, while another undercover cop Au (by Louis Koo) successfully earns their trust in an incident, a brotherly-bond is built among the three. After the Police busts the syndicate in Hong Kong, Kang subsequently hides away in the Golden Triangle, by chance he receives a tip-off about the betrayal within his circle of trust…
Sunny is a naïve circus performer who dreams of inheriting his father's knife-throwing skills. However, his hostile colleagues continue to bully him, relegating him to a lowly clown. On a tour to Malaysia, Cheung and other performers discover a cave occupied by the Japanese army during World War II. Instead of finding treasure, the performers - including Sunny - are sprayed with a mysterious chemical that turns them into superhuman mutants...