The Legend of Qin - Season 2 Episode 14 Against the Flow to the Black Turtle

Gongshu Chou opens a door on the ground and says someone has to swim in the underground river to the Waterfall and turn on one of the Four Holy Creatures, Xuanwu(the Balck Turtle) to bring in clean water or they will all die. He tells Tianming to rotate on the red handle, but when Tianming makes it to the Machine Creature, he realizes something wrong with Gongshu and rotates the black one. Clean water is brought in but Tianmign is attacked by the Black Turtle. Mohists realizes Wei Zhuang has set a trap for their appraoching allies and sends Daozhi to warn them. Wei Zhuang sends Baifeng to chase him.