The Jurchen nomads attack Nokdune while Soon-shin is away. Soon-shin returns to Nokdune with Yi Kyung-lok and the backup troops, but his brave men and the people of Nokdune are already dying after putting up a desperate fight. Soon-shin is brought to the North Base on the charges of negligence and defeat, but he fights back stating that the atrocity of Nokdune will be repeated again if he is not given a chance to reveal the truth about why the tragedy occurred. Finding his friend in trouble, Won Kyun calls on Minister of Military Chung Unshin for help. Chung's presence gives Soon-shin a flicker of hope. Meanwhile in the royal court, the Western faction sees Soon-shin's failure in Nokdune as an opportunity to weaken the power of the Eastern faction which Yu Sung-ryong belongs to, and calls for Soon-shin's execution.
—https://www.yidio.com/show/the-immortal-yi-soon-shin