It is a fictional historical drama about the story of King Seonjong who ascends to the throne due to a rebellion, and Lee Tae who becomes the King after him.
Not streaming on a subscription service in the US right now.
Starring Lee Joon, Kang Han-na, Jang Hyuk, Park Ji-yeon, Heo Sung-tae, Ha Do-kwon, Choi Ri, Kang Shin-il, Ahn Nae-sang, Cha Soon-bae