The spin-off standalone episode took the audience to when Joseon faced a possible invasion from Japan on one side and Jurchens on the other.
In the Joseon Era late 14th- to late 19th-century , when the country was recovering from the , word on the street is that the King of Joseon is dead.
First, he tips the scale of balance by diverting the Queen's army away from the city and smuggling his own men inside.
I think it's safe to assume she went half-mad after the trauma she endured Humanity has been nothing but cruel to her and her family so she plans to kill every single human on joseon and jurchen soil to avenge her family.
That caused the death of the physician's asst.
After he is resurrected as a zombie, he is hit another hail of bullets and arrows, but because none of them hit him in the head, he stays on his feet.