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…