Tang Priest and his three disciples journeyed westward. One night, they reached the vast Tongtian River, eight hundred kilometers wide with raging torrents. Unable to cross, they sought shelter in a nearby village.
They came upon the home of Chen Cheng, whose family was weeping. The travelers learned that a river spirit demanded an annual sacrifice of a virgin boy and girl from the village. This year, it was Chen Cheng's turn. Monkey King comforted the family and promised that he and Pig would pose as the sacrificial children and await the spirit in the temple.
At midnight, the spirit arrived and reached for the "girl." Pig, in disguise, hastily swung his rake at the creature, which fled back into the river. The next morning, the river was found to be frozen over. Urged by San Zang, the group attempted to cross the ice. Midway, the ice cracked, swallowing Tang Priest, who was captured by the spirit.
The three disciples pursued the spirit, but it hid in the river, knowing it was outmatched. Monkey King sought help from Guanyin, the Bodhisattva. She revealed the spirit was a giant goldfish that had escaped from the lotus pond in the South Sea. The Buddha was asked to retrieve the runaway fish.
Later, as the group pondered how to cross the river, an old turtle appeared. "I once lived here," it said. "Now that you have driven the spirit away, I have returned. Let me carry you across." The four mounted the turtle's back, and it ferried them safely to the other shore.