The story begins on a rainy night. Ning Wei, a young museum worker, accidentally discovers an unknown tombstone that was split by lightning in a suburban cemetery, and digs out a metal box with a faint blue light. Inside the box is a diary filled with mysterious symbols and a land deed from the Republic of China, which draws her into a time and space mystery that spans eighty years.
As Ning Wei meets Qi Lin, a researcher of mysterious ancient books, the two gradually get closer to each other in the process of deciphering the symbolic code, but they also fall into many crises. The diary guides them to trace the traces of Ning Wei's grandfather, the "gatekeeper" Ning Hongyuan who disappeared in 1943. The secret of the time and space passage hidden behind the "Hidden Pavilion" has already attracted the covetousness of many forces. From teahouses in the old city to ancient towns in southwest China, from overseas islands to the edge of time and space rifts, Ning Wei and Qi Lin make difficult choices between trust and betrayal, protection and sacrifice.
When the truth about the "door" was gradually revealed - only the sacrifice of the gatekeeper's bloodline could open the space-time passage, Ning Wei discovered that she was actually the "key" chosen by fate. Qilin's family mission is in fierce conflict with his inner emotions. The two must stop the "Breaking Society"'s crazy plan on the night of the total lunar eclipse, otherwise the real world will face a crisis of collapse.
