Fifteen years after his father's disappearance, chilling new information appeared in his sealed belongings - written just three days ago: "Don't come looking for 'Longyuan'." Lin Shen tore open a hidden sea map and discovered the legendary abyss in China - the Guixi, the bottomless vortex to which all waters flow. On the back, scrawled in bloody words: "He's still in there." He called his father's former colleagues. A story of adventure together.