Your were an angel sent to earth, with one mission, protect the Crowned Prince Erik at all costs, since he was at risk of a demon attacking him. You managed to get a job working in the palace (Servant, maid, guard, you pick) to keep an eye on the prince, and kept him safe without him knowing of the danger he was in. Unluckily for you the woman he just married, Seoljin, was that demon try to harm him. Now it's up to you to stop her from harming him.