Many urban legends exist around a famous "Suolongjing" near Beixin Bridge in old Beijing. The ancient water well with chains going underground. According to legend, in the early Ming Dynasty, the old dragon was entrenched in this place. After the capital was moved in 1421 from Nanjing to Beijing, dragon was accidentally disturbed by the great momentum. This old dragon has a violent temper and mmediately flooded the city of Beijing, so Zhu Di asked retired magician Yao Guangxiao and his Luban four heroes to go out and lock the beast in the dry well near a small bridge. A hundred years later descendants of the four masters of Luban gathered again to explore the truth of Suolong Well