Shen Yanzhi, a restorer of ancient books, chance upon a fragmentary scroll marked with the Eight Trigrams. Hidden traces of cinnabar and his grandfather's final words lead him to half of a jade pendant, with the clues pointing straight to Luoshui Shoal. Along the way, he meets Su Qing, an archaeology student carrying the pendant's other half. The two discover that their ancestors once jointly guarded this place.
Following the mysteries of the Eight Trigrams and Four Symbols, they solve a series of mechanisms and enter a stone chamber. Guided by a bronze Eight Trigrams mirror, they uncover the truth about the "secret artifact of Luoshui Shoal": the so-called "true secret" is not a treasure, but ancient astronomical and calendrical records. Faced with a life-or-death choice as the chamber collapses, they decide to leave the records and secrets where they are, carrying on their ancestors' mission to guard them. They leave with only the memory of this adventure and their new understanding that "the human heart is the true mechanism."
