At the beginning of chaos, the first demon in the world was born, named Yuandi, and was worshipped as the ancestor of demons. Thousands of years later, the former demon king Sun Wukong is rescued from the Five Elements Mountain by Monk Tang, who promises to protect him and go to the West to get the scriptures.
A long, long time ago, devils were rampant in East-land. Master Tang, who was second apprentice of Buddha Rulai in his previous life, swore to Leiyin Temple in West to fetch scriptures to purify East-land.