As punishment for his insolence, the spirit of Dzelu is turned into a Blue Monster and is forced to attack Nanjing and its inhabitants. Only truly faithful lovers can save him, but in order to free himself, Dzelu must doom the lovers themselves to misfortune. His victims are the Georgian princess Dardane and the missing prince of Nanjing Taer. The spirit separates the lovers and, having freed itself, turns Taer into the Blue Monster, who, under pain of death, forbids anyone to reveal his name. But the prince has only a day for Dardane to fall in love with him in the guise of the Blue Monster, otherwise he will die anyway.