In a sleazy cigar and newspaper store in Rome, an old newsagent nicknamed "Papa Re" sells his wares, warmed only by an earthenware heater that his granddaughter brings him each evening. One day, the stove falls from his hand and breaks into a thousand pieces. The same evening, when he opens the kiosk, he finds inside a woman, huddled up, with her little daughter in her arms: it is Rosalba Vignas, a singer-songwriter who has been chased away by her lover, Cesare le Milanese, who fell in love with his younger colleague.

A loose adaptation of Dr. Jekyll and Mr. Hyde.

Maciste is on the trail of a gang of criminals who have kidnapped the beautiful princess Maria Letícia de Livonia, traveling to Rome, and go to hide near a port. in this adventure, Maciste is helped by his friend, the journalist Tito Fabrizi, who was breastfed by the same woman.