Rain god Chisongzi (Adam Cheng) was supposed to take orders from heaven to rain many consecutive months to punish the humans via flood storms. However he could not bare to watch the humans suffer so much. The Jade Emperor then punishes the Rain god by sending him to be reincarnated as a human on earth.
In the Eastern Jin dynasty a fortune teller predicted that the current emperor would be overthrown by someone born on August 23 that year. The emperor ordered all babies born on that date killed. But even after the mass execution, the emperor would continue to have reoccurring nightmares about being assassinated. It turns out his own son, Prince Lung (Patrick Tse) was born on that date and ended up killing him. Lung would bring a lot of troubles to the kingdom in an effort to become the next ruler.
Rain god was now reincarnated as Wong Zo-ping, a miracle doctor and healer who tried to help many people along the way. Later Wong Zo-ping becomes heavenly deity on earth Wong Tai-sin to face off against the corrupt empire. He would eventually become a legendary icon.