It all began during the Zhenguan era. The four members of Tang Sanzang's party completed their 108,000-li journey to obtain the scriptures, overcoming eighty-one trials before finally reaching the Thunderclap Monastery in the Western Heaven and obtaining the true scriptures. They were each granted titles: the Buddha of Sandalwood Merit, the Victorious Fighting Buddha, the Messenger of the Pure Altar, and the Arhat of the Golden Body. Buddhism's merits were complete.
Under the pretext of "saving all living beings in the Eastern Lands," the Tathagata ordered the four to set out from Mount Ling with the scriptures, travel to the Eastern Land of Great Tang, and deliver them to Emperor Taizong, completing the final step in transmitting Buddhism eastward.
Yet this seemingly triumphant return marked the beginning of the four disciples' total break with Buddhism and their journeys toward their own fates.
On the road east, the four discovered a truth that overturned everything they believed: the farther a place was from Mount Ling, the more favorable the weather and peaceful the people, who suffered neither hunger nor cold nor demon attacks. But in Xiniu Hezhou, closer to Mount Ling, living beings suffered terribly and the people could barely survive. Everywhere were commoners exploited by gods and Buddhas, and villages ravaged by their mounts and attendants.
What drove the four to despair even more was that every demon causing trouble along their journey east turned out to be a mount, attendant, or trusted retainer of Buddhism. Every tribulation had been secretly arranged at Mount Ling, all part of a deliberate scheme. The so-called "salvation of all living beings" was merely Mount Ling's attempt to control the Eastern Lands through the scriptures. The so-called "return to the true path after eighty-one trials" was nothing more than gods and Buddhas toying with mortals.
The four witnessed the injustice of Buddhism and its distortion of right and wrong with their own eyes. Their initial doubts gave way to shattered faith, and in the end, they all broke with Buddhism, each heading toward a fate completely opposite to the one in the original novel.