A vicious killer named Fung goes around Hong Kong killing top martial arts exponents and leaving a secret weapon called the Moonshadow as his calling card. When a convicted killer and kung fu expert named Ha - formerly working as a martial arts instructor before accidentally killing a man and being imprisoned and convicted for the crime he didn't intend to do - hears of this, he offers to help the police catch the killer in return for his freedom. With Ha's help, the police realize from the...