"Castle" is the infamous crime syndicate of South Korea, wielding unparalleled power. Shin Kim, a Korean-born Russian assassin known as the "Amur Tiger," has returned to his homeland to dismantle the syndicate's tyrannical rule. He answers the call of his late mentor, Min Sung Kang, and ventures into the crime-infested city of Hoe-Am with his allies. Together, they brave great danger to confront "Castle" in an ultimate showdown.