Maciste takes advantage again of a break of acting in order to wash away injustice and castigate the wicked, this time in the name of dynastic legitimacy. Otis, the prince of Sirdagna kingdom, lives undercover in a foreign land, waiting to ascend the throne; Stanos the evil ruler though, is willing to do anything in order to prevent the legitimate prince installation. The court is a dangerous place, Otis is young and naïf: in order to solve the situation, Maciste, following the advice of his friend Saetta, temporarily takes Otis’s place, and presents himself as the legitimate prince. The crowd, enamored by his good looks, applauds him immediately as the emperor.