The Ugly Duckling is a comedy play by A. A. Milne, which has nothing to do with the Hans Christian Andersen story. In the play, a King and a Queen have a hard time marrying their daughter, an ugly princess. They devise a scheme to marry her to a prince from a far away land. To every suitor they ask a ridiculously easy question, in the hopes they will marry the princess. But the princess is so ugly that all the princes guess wrong. So, to meet the next suitor, the Princess Camilla disguises herself as her maid Dulcibella, while Dulcibella pretends to be Princess Camilla.

However, Prince Simon has also disguised himself as his servant, and dressed his servant up as the prince because he felt he wasn't handsome enough. Before the marriage of the two servants dressed as royalty, the real prince meets the real princess and they reveal their identity and begin to understand each other.

Prince Simon tells Princess Camilla that she is very beautiful, although all other princes have found her to be hideously ugly. Then the princess reveals that she was given a gift from her great aunt that would make everyone ignorant of her real beauty, so that she wouldn't grow up vain - until the day she met her one true love. The play ends with the marriage of the disguised servants, and the princess's mother wonders why Princess Camilla is suddenly beautiful.