Taealha prepares Tagon for his meeting with Eunseam; Mihol tries to convince Asa Ron to divulge the truth; Tanya has a vision.

After a chance encounter, Tanya begins to grasp the meaning of the dream. Tagon's plan disturbs Taealha. Mubaek discovers something astounding about Eunseom.

Saya has a message for Taealha, Tagon strengthens his hold on Arthdal, and Tanya receives news regarding Eunseom.

It has been eight years since Tagon was enthroned as the reincarnation of Aramun; Eunseom, the reincarnation of Inaishingi, dreams of liberating everyone who is persecuted and crosses the Notsan River.

The first war between Arthdal's army and the Ago Union takes place on the Hanchoa Plain; Eunseom and the Ago Union struggle with the overwhelming power of Arthdal's elite forces; Tagon realises Tanya's heightened position and feels threatened.

Arthdal gets shocked and confused at the unexpected situation in the first battle with the Ago Union. The Ago Union fear that what brought them together for the first time in 200 years might fall apart.