Lin Fan is drawn into the mysterious dungeon known as the True Dragon Domain, only to discover that he possesses numerous skills and has even killed a divine official in the past. Yet he remembers none of these experiences. The black umbrella in his hand strikes fear into the Apostles, while an old diary warns that there is no way out. Traveling with three companions, he tries to unravel the rules of survival while investigating his lost memories. But the closer he gets to the truth, the more he suspects that something far more dangerous than the dungeon itself might be the person he was before losing his memory.