Four "three-floor" buildings survived magically after bombing by Japanese solider, how did these buildings survive? Why the brothers of Sun family built "three-floor building"? What were the secrets under the base of this building? Why did they disappear suddenly? ...... The stories caused by mystic flag had so many suspicions. There were so many things that we could not understand. It seemed that only Naduo himself could reveal the secrets. So Na Duo and his partner went to the building to explore the myth...... The result would be unexpected!