An armoured truck carrying $100 million of cash is attacked by a criminal gang who call themselves the "Ronin Gang" with explosives as it stops at a traffic junction in front of a jewellery shop. All the security guards are shot dead except one, while responding police officers suffer serious casualties under the gunfire of the heavily armed gang members. The explosions also kill several civilians, including a lady in the shop. Six months later, the same gang reappears in Hong Kong, injuring a group of policemen, two critically, during a spot check. The dead woman in the jewellery shop is CID detective Chan Chun's fiancée, while the injured policemen are led by Trainee Inspector Carson Fong Yik-wai. Both officers vow revenge on the criminal gang.