Two brothers, peasants, want to get rich. Their father, long since dead, was a knight, their mother is a simple country woman. The elder brother, Arbogast, saves the life of a noblewoman when she is out hunting and falls hopelessly in love with her. And, would you believe it, she is one of the prizes awarded by her father, King Charlemagne, for returning to him a valuable battle horn which is now kept in the land of the Mohammedans, that is, the Spain of that time! Arbogast sets out on this quest together with his brother Eric. An astute country lad, Arbogast succeeds where all the well-armed Christian knights fail and he now intends to return to his native country to claim his reward.
However, his villainous brother Eric absconds with the horn and, consequently, with a large estate and the princess. Boasting of exploits he never performed, he receives the name of Eggeric: ”Ruler by the sword”.
Arbogast has taken up a criminal career and has become the leader of a gang of robbers and now bears the name of Elegast: ”Lord of thieves and elves”. Elegast spreads fear, destruction and poverty among the nobility, who blame King Charles for all this and are now conspiring to murder him.
In a prophetic dream Charles is warned by angels that his final hour has come unless he goes out to steal. This he does and he happens to meet Elegast. Through him Charles finds out about the conspiracy. With the help of the gang of robbers he manages to save his Royal Skin. Then there follows a single combat between Eggeric and Elegast, a trial by battle, the outcome of which must decide which of the brothers is the villainous liar, which the noble hero. And as befits fairy-tales, the Good Guy wins: Elegast.