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It is the year 1388. General Lee Seong Gye is dispatched to invade the Liaodong Peninsula but decides to retreat. King Woo of Goryeo, enraged, orders to arrest all the family of General Lee. The general’s son, Lee Bang Won, manages to elude the chase of soldiers and heads to Pocheon to save his family.
After a fierce battle, the royal palace falls. Lee Seong Gye cannot bear to become a traitor and makes his army wait outside instead of taking over the palace. However, King Woo finds it hard to accept the defeat and organizes a surprise attack.
Lee Bang Won learns that assassins got inside the home of Lee Seong Gye. He rushes to the mansion to find his father still safe. Much relieved, Lee Bang Won approaches Lee Seong Gye, but at that moment, the men with swords jump at the father and the son.
King Gongyang has shamed Lee Seong Gye in public. Unable to tolerate the insult his father suffered, Lee Bang Won visits the king and conveys a sharp warning. Terrified, the king issues an order to decapitate his predecessors, Woo and Chang. A confounded Lee Seong Gye implores the king to withdraw the order of beheading.
Lee Seong Gye gives up everything and leaves for Dongbukmyeon. Lee Bang Won fails to dissuade his father from leaving and feels frustrated. Meanwhile, Jo Yeong Mu, who has joined the journey to Dongbukmyeon, asks Lee Seong Gye to go back to Gaeseong and become the king, telling him that they will not be welcomed in their hometown in the present situation. Lee Seong Gye has to think and make a decision now.
Jeong Do Jeon dashes toward the Cheongju Prison, and so does Jeong Mong Ju. But both are held back midway by a downpour, which cut off all the roads to the Cheongju Castle. The prisoners, who belong to Jeong Mong Ju’s faction, are destined to die if the rain should continue to flood the Cheongju Castle. The two men watch the endless heavy rain, each waiting for fate to decide.
While hunting in the woods, Lee Seong Gye is critically injured when he falls off his horse. Jeong Mong Ju takes this opportunity to exile all of Lee Seong Gye's followers. The Lee family does not know what to do and waits for Lee Seong Gye to wake up. Then, Lady Kang asks to see Bang Won who is carrying out a three-year memorial ritual for the late Lady Han.
Despite his father's order not to touch Jeong Mong Ju, Bang Won defies him and is determined to put an end to the chancellor's life. The death of Mong Ju has given Lee Seong Gye a chance to retake the throne, but as much as the General respects Master Poeun, he banishes Bang Won and his brothers from the house for disobeying his intentions. Now with Jeong Mong Ju gone, the fate of the throne lies within the hands of the family of Lee.
After Master Sambong reorganizes the court officials, he and Lady Kang succeed in persuading Seong Gye to take the throne. Thrilled by the news, Bang Won and his brothers attend the coronation. But as they reach the palace, they only find disappointment. Seong Gye is now in deep thought of who to appoint as the Crown Prince. He is aware of his old age and wishes to appoint the Crown Prince quickly.
Bang Won hears the news that Bang Seok will be installed as the Crown Prince. Full of rage and disappointment, he finds his brothers to stop it from happening. However, his brothers have given up on taking a position in the palace. Meanwhile, Lady Kang is extremely happy as her meticulous plan that she has been working on for years is finally coming into place. With her son appointed as Crown Prince and herself as the Queen, nothing can stop her now.
Bang Won is furious as he sees Queen Sindeok act with hypocrisy. Although he wishes to rash out on the manipulative Queen, Lady Min settles him down and tells him that the time to strike back will come. As the King leaves the palace for a trip, the Queen plans a trap to get rid of Bang Won for good. She tampers with his family member and lures him to attack her with his House Guard soldiers.
Bang Won sets off to Ming to stabilize the diplomacy. Although Queen Hyun is happy about having rid of Bang Won, bad news starts to pile on her. Meanwhile, Bang Won's audience with the Emperor of Ming goes better than expected. He returns home safely into the arms of his beloved wife, Lady Min. However, there are changes at the Palace that Bang Won must deal with. Perhaps these changes can become a chance for Bang Won to thrive.
Lee Seong Gye accuses Bang Won responsible for the early death of Queen Hyun. Although Bang Won pleads his innocence, the King is blinded by the sorrow of losing his beloved Queen and cuts ties with Bang Won for good. Lady Min becomes outraged as she sees her husband being treated wrongfully. While Bang Won recovers from the shock that his father has given him, Lady Min tries everything in her power to make a spark of rebellion.
Bang Won starts planning details of the rebellion and begins training his soldiers for the battle to come. However, Seong Gye is fast-witted enough to realize that Bang Won is up to something. Although he tries to disband Bang Won's soldiers and take him in, he does not have enough evidence to do so. On top of that, the Emperor of Ming is also causing a problem. Both domestically and diplomatically, Joseon faces many hardships to go through.
Lee Seong Gye declares that he will wage war in the Yodong Peninsula with all the private soldiers he has absorbed into the Three Armies Command. Several of his court officials beg him to reconsider, but he is adamant. Meanwhile, Lee Sook Beon and his soldiers appear in the Capital. Bang Won sees this as an opportunity to reignite the flames of rebellion.
Master Sambong finally determines to get rid of Bang Won and the other princes. However, as the assassination ends up a failure, it only provokes Bang Won to proceed with his rebellion quickly. Now, all soldiers from various parts of the country gather to follow Bang Won into the palace. With the King bedridden and the Crown Prince too scared to do anything, the palace remains defenseless. The future of Joseon now depends on the consequence of this rebellion.
Bang Won's rebellion proceeds exactly as planned. Although he spares his father, he puts an end to those who are loyal to Jeong Do Jeon. Just when things seem to go well, unexpected casualties also occur. Royal blood that should not be split has been shed unrelated to Bang Won's wishes. He becomes confused whether he is a bloodthirsty beast or a man who wants to accomplish a great cause. Regardless, Bang Won now holds the most power in Joseon.
Sang Gu continues to threaten Sa Ra for money, and when that doesn't work, he decides to use Se Jong as bait. Se Jong nearly gets into an accident while running away, and Dan Dan gets injured while saving him. Meanwhile, Ki Ja gets caught for stealing Dae Ran's gold and money, but this leads to Young Guk finding out about the whereabouts of his mother's diamond ring.
Lee Bang Gwa is fully determined to keep the throne and protect it from Bang Won. Although Bang Won is already distressed with Bang Gwa and Seong Gye, his other brothers raise an army against him. Bang Gan and Bang Ui take action and wage battle against Bang Won. Despite Bang Won's sickness of fighting his brothers, he yet once again must draw his sword against family.
Bang Won successfully suppresses Bang Gan and heads directly to the Palace. Despite their differences, Bang Won and Bang Gwa have the same desire to stop shedding family blood. Hence, Bang Gwa decides to hand over the throne to Bang Won peacefully, and Bang Won decides to spare Bang Gan his life. However, Seong Gye is not satisfied with Bang Gwa's choices and plans his own schemes.
