Iron Coupon Puzzle

Lin Zhaoyuan, the son of a down-and-out prince, went to Beijing to redress his grievances with the "iron coupon" left by his late father, but found that the royal seal on the iron coupon had been tampered with. It was no longer an amulet, but a reminder that "this person must die". In order to uncover the truth behind the unjust case of his father's "collaboration with the enemy", he was forced to be involved in a shocking conspiracy that spanned ten years and related to the change of imperial power. In the capital city where murderous moves were taking place, he joined forces with Liu Ruyan, the missing daughter of the commander of the Forbidden Army, to fight against the powerful chief minister Gu Tingfang and his gang members.