Rookie police officer Yam Hoi is a recent graduate of the police academy. Due to a wave of serial killings, Hoi is partnered with Brother Chin, who was recently reinstated on the force. However, the duo is unable to solve the cases and instead causes a series of incidents. Later, Chin re-encounters a street child, Wong To, who murdered his wife and son, and his anger makes him spiral out of control. Hoi clumsily loses his pistol, which is found by the serial killer. With the killer lurking in the city, a crisis grows closer.