Lin Yuan picked up an iron token in the scrap pile, which contained a three-dimensional map woven with metal wire. An X-ray told him: This is not an antique, but a key. The iron talisman points to a collapsed stone chamber - eight characters are carved on the stone wall: No opening unless it is twelve, no return unless it is Yuan. From the Panjiayuan street stall to the Tusi official village in western Sichuan, from the Dunhuang caves to the Lop Nur Gobi, he followed the direction of the iron talisman all the way west. Every time he solved a clue, the secret became deeper. Until he discovered that there was more than one piece of this thing. Twelve iron talismans spelled out a truth that he could not imagine
