Arang and the Magistrate is based on a Korean folktale about a ghost who asks a magistrate to solve her murder. Adapted into a fusion sageuk, it is, naturally, now also an action packed romance. (One destined to end badly given the whole "our heroine is dead" bit. Unless she ends up possessing someone else's body for good, which would be an entirely different kind of bad ending...)
While there are definite horror elements, it's more supernatural mystery than horror. Arang remembers nothing from before her death, and has accidentally frightened the last three magistrates to death when she tried to approach them for help. Until Our Hero, Eun Ho, came along, the only human she could interact with was Bang Wool, a female shaman who can hear but not see Arang. Eun Ho is the son of the former prime minister and a slave who is looking for his mother, who disappeared years ago, and tries very hard to ignore injustice and people in need, but isn't incredibly good at it. There's no explanation yet for why he can see ghosts.
There's also Moo Young, a grim reaper who is supposed to capture Arang and take her to the underworld (but doesn't seem to be trying TOO hard), and Joo Wal, the strange son of the local lord who is possibly connected to Arang and either is secretly evil, cursed, or possessed. Yoo Seung Ho also randomly pops up as the Jade Emperor and is clearly having the time of his life.
The soundtrack is engagingly anachronistic and so far the writing is excellent. The plot is very much Serious Business but the show manages to frequently be hilarious, largely due to how Shin Min Ah and Lee Joon Ki deliver their lines and bounce off each other (though everyone that's needed comedic timing to so has been excellent at it). Also, I'm glad that instead of the typical "rough around the edges hero who will be Redeemed By Love," both leads are rough and on the crude side and have more than a bit of a bully in them (her more than him for the last part). I'm not sure how they'll maintain the plot for 20 episodes but I have high hopes.
Some spoilery comments:
It really seems too easy to have Arang's identity discovered this quickly? I'm actually thinking that the old magistrate had two daughters and one was the daughter of one of his slaves and Yoo Wal fell in love with the wrong one and either her father had her killed, or Yoo Wal killed her himself during one of the...violent thingies he seems to have. (Perhaps possessed by the spirit of an evil dead twin?) I'm sure I'll change my mind frequently, but I'm pretty sure Arang mistook fear for crushing (It's not like she'd ever believe she could be scared of a human...)
Also, I'm thinking that Moo Young's sister is either Arang or Eun Ho's mother? At first I wondered if he could be Arang's brother but (1) he'd have to be WAAAAAAAAY older as he was already a Grim Reaper when he died and (2) even if he didn't know who his sister was, I doubt the Jade Emperor would rely on him to drag his own sister to the underworld.