In 600 BC, Babylon is conquered by the army of King Assur. When the Chaldean people refuse to submit to his rule, their leader Ahmal (Montalban) flees into the country and is hidden by a beautiful goatherd named Semiramis (Fleming). She is later captured, becomes the King's favorite and is soon made queen. When Ahmal himself is made a prisoner, he believes she has betrayed him. The king's wicked cousin tortures Ahmal and uses both him and Semiramis in his plot to depose the king and seize power for himself. When he does murder Assur, he blames Semiramis and prepares to burn her at the stake. But Ahmal and his people, toiling as slaves in a nearby quarry, are alerted by an informant...