The mighty warrior Ursus, who fought for years in the army of King Alteo, has retired from the military to run a farm in the countryside with his little brother Dario.

When some rebels in Zagro's court free the boy from his captivity, Ursus is able to escape from the slave camp without fear of endangering his brother's life, and the two head back to King Alteo's kingdom, to warn him that he is about to be assassinated.

Ursus uses his great strength to resist the mammoth creature, and succeeds in convincing the people that Zagro was behind the assassination of their king.

During the chaos, Ursus stabs Zagro to death with his own sword, and liberates the people, as well as Princess Sira.

Sira takes over the throne, and asks Ursus to rule at her side, and the populace celebrates their newfound freedom.