History professor Zhou Yuan received a letter from 1943. The sender was his grandfather Zhou Huaimin, who had passed away long ago. The letter mentioned a batch of national treasure-level bronzes that mysteriously disappeared during the Anti-Japanese War. Zhou Yuan and cultural relic restorer Lin Xi followed the map and found nine heavy bronze artifacts that had been sealed for more than 80 years in an abandoned air-raid shelter in Jiuli Mountain, Xuzhou. What's even more shocking is that there was a skeleton wearing a modern jacket in the cave, with Zhou Yuan's own business card in the pocket.
Time and space overlapped in this underground air raid shelter. Zhou Yuan discovered that his grandfather was not only a rescuer of cultural relics, but also the guardian of an ancient time and space device - there is an ancient stone disk hidden deep in the Jiuli Mountain that can briefly overlap time. As the truth is revealed layer by layer, the transnational cultural relics smuggling group "Mr. Black" and the remnants of Japan's World War II surface at the same time. The secrets left behind by my grandfather before his death are far more than just twelve national treasures...
