Deramo, kind, but simple-hearted king of Serendippe, wishes to marry. But here's the problem: how to find out which of the contenders really loves Deramo, and which one simply counts on the royal throne? The wizard Durandarte gives the king a statue of a fool who laughs if someone says untruth. Outwardly, the idiot is similar to the favorite of the king by the first minister, the crafty and mean Tartaglia, who for a long time and unrequitedly was in love with Angela, the daughter of the second minister, Pantalone, a timid chinovopitaltsa. But she herself loves Deramo, although she does not want to go to the bride, considering them unnecessary and humiliating. Tartaglia plaits intrigues and in every possible way interferes with his daughter Clarice to marry young handsome chamberlain Leandra, brother of Angela, expecting to give her daughter for the king. Despite all the tricks of the first minister, the king, on the bride-show, under the audacity and sharpness of Angela, managed to discern love for him, falls in love with her and declares his wife. However, Tartaglia is unrelenting: on hunting, he learns from a friend the spell of Durandarte and changes his bodies with him.