A long time ago, somewhere in the mid Joseon dynasty, the kingdom experienced an uprising when a group of power hungry members of the court plotted treason against the throne to gain more power in the Royal court.
When queen Soo Young could not bear any children for the king Sungho, she adopted prince Hoo Myeong, the first son of the king by his first senior consort Yoo Bin, who was also a cousin to queen Soo Young from her mother's side. Consort Yoo Bin was the most favored among the king's women, and even though the queen was in charge of the affairs of the inner court, consort Yoo Bin had the king's heart and ear. He loved her so much that she could influence some of his official decisions in court as the king confided in her on matters of state. Knowing the power that she had over the king, some of the court ministers began to seek consort Yoo's assistance in turning the tides of the discussions in court to their favor. Her father, Kim Il Jung who was the left state councilor, took advantage of his daughter's place in the king's heart to grasp power, and several members of the court became loyal to him as he spoke to his daughter on their behalf.
Left state councilor Kim Il Jung's thirst for power became excessive and he began to seek even more power and position. When queen Soo Young's father, who was the chief state councilor, passed away, Kim Il Young tried to convince the king, through his daughter, to appoint him into the position. But when the king would not listen to him and appointed someone from the other side of the hall, councilor Kim Il Young became outraged and vengeful. He began to seek for a way to get back at the king, which led him to begin plotting treason.
Left state councilor Kim Il Young became impatient as he longed to have more control over the court as soon as possible, especially as the king had stopped listening to his daughter Yoo Bin, and was listening more and more to the chief state councilor, who advised the king to make decisions that didn't always favor councilor Kim Il Young, nor his side of the court.
When consort Yoo Bin's son, Prince Hoo Myeong was appointed as the crown prince, his grandfather devised a desperate plan to slowly poison the king and bring him to an early death, so that he could install his grandson as king and have more say in court. He recruited the help of his daughter, consort Yoo, to sneak the poison in doses into the king's tea. But the poison was just a a small part in councilor Kim Il Young's grand plan to overthrow the king, as he already had plans for a rebellion on the way, just in case all else fails.
The secret began to come to light when a court maid in the service of the queen reported a suspicious exchange she had witnessed between a court lady who served at consort Yoo's quarters, and another court lady in charge of serving the king's meals. The court maid happened to report her observation to the personal guard of prince So Hyeon, the wild but wise second elder son of the king by his second senior consort.
So Hyeon secretly began an investigation into the report, and when he had the court ladies interrogated, the brewing rebellion was brought to light.
There was a purge, which led to the execution of consort Yoo, her son, her father, minister Kim Il Young, and every other member of the court who were found linked to the rebellion.
Unfortunately, the king's health had already deteriorated beyond redemption, and coupled with the shock of the betrayal he suffered at the hands of his favorite consort, the king could not survive for very long. The king died briefly after the purge and prince So Hyeon was crowned king.
King So Hyeon restored balance to the court and ruled with an iron fist over his ministers, to make sure that none of them would try to rise against him the way they had done with his father. He was successful in returning peace to the land after it had been shaken by the purge, and he led an inclusive government where both sides of the court were carried along in all matters of the state. The people were happy under his reign and there was no abuse or imbalance of power in court.
The king was successful in all his deeds, but he lived with a constant shadow hanging over him. There was a possibility that the purge had not been completely done because just before the purge began, the court maid who had informed the personal guard to the king about the court ladies, had disappeared after leaving a cryptic message. The message was unclear, but it insinuated that someone who lived in the palace other than consort Yoo had been involved in the rebellion too. 'An upper hand'.
After the maid disappeared, king So Hyeon remained apprehensive and lived everyday dreading the fact that someone who had played a part in the plot of a rebellion which led to the death of his father, still lived within the palace. There was no way to tell who it was or if it was true, since the maid was nowhere to be found. King So Hyeon decided that she was most probably dead, possibly killed by whoever it was that she had discovered. He couldn't do much without more information, so as a precaution, the king sent off all of his father's concubines who had sons. He had their sons married off and sent them to settle at distant provinces.
Still, king So Hyeon lived under the constant shadow of a rebel lurking somewhere in the palace, or around the city. Meanwhile he continued to search for that court maid, hoping that she would still be alive so that she could come around and identify the last strand of the rebellion, before it could gain any momentum and rise against the kingdom once again.