Haechi - Season 1 Episode 37 The Plague
Overview: An unidentified plague starts spreading from the southern provinces, and the capital city is soon affected. The commoners start to blame the king who supposedly killed his brother and took the throne. Prince Milpoong and Wi Byeong Joo escaped from their exile place and followed Lee Yin Jwa as he prepares for a revolt. Also, Queen Dowager falls ill from the plague.