16 Episodes · Premiered April 17, 2020 · Ended June 12, 2020
The King: Eternal Monarch traverses dimensions and time. When a demon opens a portal into another world, science-minded Korean monarch Lee Gon must find a way to shut that door in order to stave off disaster. On the other side of that door is a modern-day South Korean police officer, Detective Jung Tae Eul, whose priority is saving lives and protecting the people she loves.
Lee Gon mourns the tragic death of his father. Lee Lim goes on the run - and finds escape when he comes across a door to a parallel universe.
Gon insists he's an emperor from another world. An incredulous Jeong Tae-eul takes him to the police station, where he sees a familiar face.
Though Tae-eul finds Gon's story difficult to believe, some things about him are completely inexplicable. At work, she gets busy with a murder case.
When Tae-eul loses her police badge, she can't help but think about Gon. Meanwhile, Kang Sin-jae has had it with his mother's bad habits.
Being introduced to Gon's world is a lot to process for Tae-eul, who's taken to the palace. A disgruntled Jo Yeong keeps an eye on her.
A potential military conflict theatens the kingdom. Gon promises Tae-eul he will return to her, and steps forward to take care of the situation.
Gon brings Yeong along on his trip back to Tae-eul. He has a favor to ask of her, while she's found something troubling to share with him.
In Corea, Luna is set free. In Korea, Gon and Yeong run into a man who recognizes them, and Sin-jae experiences childhoos flashbacks.
Gon draws closer to tracking down Lim, and asks Jo Eun-sup to trade places with Yeong. Mail from an unknown sender bothers Koo Seo-ryeong.
On Lunar New Year, Gon and Lim come face-to-face in a public standoff. Tae-eul opens up to Sin-jae about the other world and her ongoing case.
A compelling offer finds its way to Luna. Gon's investigation into a devastating murder leads him to an old traitor and a clearer idea of Lim's schemes.
Frightening circumstances land Tae-eul back in Gon's arms. When Yeong runs into a woman who looks strikingly familiar, he follows her.
Knowing Seo-ryeong is up to no good, Gon throws her in a tight spot. Upon returning to her wordl, Tae-eul realizes Luna is there, too.
Gon and Tae-eul are separated when he sets out to fulfill what's been his fate all along. Sin-jae makes a startling discovery.
Lims plots his next meeting with Gon. Understanding there's only one thing he can do to right wrongs, Gon comes to a heart-wrenching decision.
A final attempt to put a stop to Lim's ambitions comes with profound consequences. Gon travels far and wide in search of Tae-eul.
