Eight years has passed since Tagon took the throne as the second coming of Aramun. Eunseom succeeded in uniting the Ago clans as the second coming of Inaishingi and he leads them to the great war against Arthdal. Meanwhile, Saya must prove his worth to succeed Tagon.
The first battle between Arthdal, led by Saya, and the united Ago forces, led by Eunseom, takes place in Hanchoa. Eunseom and the Ago forces gets overwhelmed by Arthdal's military power. Meanwhile, Tagon realizes the elevated status of Tanya as the second coming of Asa Sin and begins to feel threatened by her absolute power.
The united Ago forces faces an unforeseen situation, causing anxiety among its leadership that the alliance, which has been unified for 200 years, may fall apart. Meanwhile, Tanya is confronted with a truly incredible situation.
The final battle between the Ago Union and Arthdal has come. Tagon prepares for a personal war. Tanya, Taealha, Saya, and Eunseom make one final move to protect what's most precious to them. Who will take over Arthdal?