The King is in love, but Dong Yi is having trouble in her new role. This is because the court lady doesn't want to work for her. But things get from bad to worse when Dong Yi's maid starts to get sick. The King then takes Dong Yi to their favourite tavern and when they get back to the palace, a strange plague has spread. Strangely, only the court maids are infected. Then, Dong Yi is under suspicion of trying to kill the Crown Prince. Unfortunately for Dong Yi, Jang Ok Jeong is in charge of the investigation and she is only being given three days to find the cause of the plague. She will be killed if she fails.