University student Souma is suddenly summoned as a hero to the kingdom of Elfrieden, which is facing a number of crises, both foreign and domestic. Souma confers with the king and prime minister, after which the king makes a stunning announcement.

The Three Dukes meet to discuss what to do about King Souma. In Amidonia, Gaius receives word from Georg accepting his aid, and prepares to invade Elfrieden over the objections of his finance minister. Souma delivers his ultimatum to the Three Dukes.

Gaius leads an invasion force from Amidonia into the kingdom and lays siege to the city of Altomura. Meanwhile, in Randel, the Forbidden Army constructs a fort from which they engage Georg's forces, while Red Dragon City receives its own surprise attack.

Souma and his entourage confront Vargas in his castle before hurrying off to Randel to regroup with the Forbidden Army. A stunning truth about Georg is revealed by Glaive, leading to a dramatic turn of events with Gaius and his forces at Altomura.

Souma is victorious in both the Elfrieden civil war and the battle against Amidonia. However, his victory was won as a result of the devotion of a man named Georg. Still, the law is the law, and Souma must pass down a harsh judgment against Georg.