During an operation with a master criminal, an undercover cop fails his mission because he was shot by an uniform officer. His superior suspects he has become a bad seed and refuses to allow him to rejoin the force. In order to prove his innocence, the cop decides to follow the thief to the Sino-Russian border on an arms struggle deal, but on the way they are chased by Mainland police. During the escape the cop and the criminal become friends. When they return to the Hong Kong border, the police awaits on the other side and...