I loved it. The cast and writers did a awesome job It was a little confusing at first and you really needed to pay attention to what happens in both world of 2019/2020 and it all came together.
It start 1994 with li gon watching his father being murdered by his brother/uncle yi rim/Lee seong jae and then he try to kill his nephew, but is interrupted by someone helping him. It turns out the uncle wanted magic flute that could open up to paraell worlds. Li rim escapes with only half the flute and while running in the bamboo tree he open a door to a paraell country call the republic of Korea. Then 25yrs goes bye a blimk