Chun-su makes a trip to Andong for the company instead of Soon-shin so that Soon-shin would not miss his archery contest, but he makes a huge mistake during his trip. Chun-su grows increasingly despondent as he realizes that nothing goes right for him while everyone seems to hold his friend Soon-shin in high regard. Baron Huh and Song Tak decide to test Soon-shin's loyalty to the company and sends Soon-shin to Ahsan to collect salt tax. It turns out that Baron Huh was the one who had been exacting usury from the naive salt farmers of Ahsan. When Soon-shin finds out about their unlawful activities, he returns to Hanyang to discuss the situation with Sung-ryong. Sung-ryong begins an internal investigation which reveals involvement of a Royal kin Yoon Won-hyung.
—https://www.yidio.com/show/the-immortal-yi-soon-shin