Baron Huh frames Chun-su and Supervisor Kim for all of his criminal activities in the salt tax collection and points to Soon-shin as the snitch causing division between Chun-su and Soon-shin. Chun-su and Supervisor Kim are arrested and tortured by the authorities. All of the physical evidence that point to Baron Huh for the crime disappears. Yoon Won-hyung had acted quickly and gotten rid of them. Lack of evidence causes the royal court to stop the investigation. Soon-shin tries desperately to save Chun-su, but it's hopeless. He goes to the Royal Repository where the two men are being held and finds out from Supervisor Kim where Baron Huh keeps his books. With the incriminating books in possession, Soon-shin makes a deal with the baron. Chun-su is freed, but infuriated baron orders Chun-su to frame Soon-shin.
—https://www.yidio.com/show/the-immortal-yi-soon-shin