The fourth episode of 500 Years of Joseon Dynasty covers the first half of the 16th Century, from the reign of Jungjong to Myeongjong. The drama focuses in particular on the court intrigue surrounding Jung Nan Jung, the scheming concubine of Prime Minister Yoon Won Hyung, and Queen Munjeong, who held considerable power as Queen Regent for her son Myeongjong and continued to do so even after he reached maturity.