Dark River, the most mysterious assassin organization in the martial arts world, is composed of the Su, Xie, and Mu families, each with its own patriarch as their highest leader. The patriarch is suffering from a rare poison and his life is hanging by a thread. Upon learning this, the three families of Dark River seize the opportunity to launch a rebellion. Su Muyu, as the leader of the Spider Shadow Guard, seeks out the renowned physician Bai Hehuai from Medicine King Valley to treat the patriarch while simultaneously repelling assassins from various families to protect him. Meanwhile, his close friend from Dark River, Su Changhe, joins the assassination attempt on behalf of the Su family.