How did Zhang Qiling and Xiao Ge get out after entering the third level?

After Zhang Qiling and Xiao Ge entered the third floor, there was an open key on the door. They pressed it and came out. According to the relevant information, the down-and-out writer visited an antique shop owner named Wu Xie for writing materials, and Wu Xie was about to leave the city. Before he left, Wu Xie told him about his strange family who robbed tombs, and about the strange incident he experienced with his family for the first time: that time, their family accidentally acquired a special bronze ware, which traced back to the source. They discovered the ancient kingdom of the Queen Mother of the West buried in the northwest basin of China. They recruited a group of grave robbers, explored the ruins of the ancient city together, entered the tomb of the Queen Mother of the West, which is located underground in the ancient city, and discovered the truth that Zhou Muwang begged the Queen Mother of the West for longevity in Immortal Technique. After listening to Wu Xie's story, the writer found many doubts. Wu heterodox is his own imagination, or the truth is more terrible and complicated, because Wu Xie's departure has become an eternal mystery.