Sima Jun, portrayed by Lo Lieh, is a merciless assassin serving a ruthless lord, executing orders without doubt. When the lord develops a dangerous boil, the Imperial physician reveals that only the rare "Longevity Rattan" can save him, cultivated by a reclusive herbalist named Tan in a distant village. Tasked with a desperate mission, Sima must navigate the treacherous journey to retrieve the herb and save his master before time runs out, facing numerous challenges along the way.