Goguryeo has been on the decline since the passing of Jumong, and King Yuri's authority is challenged by Jega, the board of tribal chiefs, who plot to overthrow the king.

King Yuri struggles with the prophecy of the newborn baby leading to Goguryeo's demise, and with the pressures to kill the baby. He decides to send his son to Hyeap of Giraffe Cave, and have him secretly raised as a common-man.

To save Hyeap from the assassins of Buyeo, Muhyul heads for Jumong's tomb. Legend has it that no one has ever come out alive, and whomever takes possession of the mythical sword will dominate the North.

While his father King Yuri is in Buyeo castle befriending King Daeso, crown prince Haemyung and his army head to rescue Muhyul, who has been captured and tortured.

Concerned for Goguryeo's future, Haemyung starts scheming the assassination of King Daeso, while the palace of Buyeo becomes alert of the potential danger.

Haemyung attacks King Daeso on his way to Hwangryong Kingdom, and Goguryeo sends a scout to confirm Daeso's death. Upon receiving the news Jega board grows concerned that King Yuri is getting too strong.