Carcassonne: Princess & The Dragon - Rules of Play says:

In this third major expansion for the prize-winning Carcassonne, we move into the realm of fantasy. The land around Carcassonne is being visited by a dragon, making life very difficult for everyone. Brave heroes venture forth to face the danger, but without the aid of the fairies, their chances are not good. In the city, the princess seeks help from the knights, and farmers build secret passages to move about undetected by the dragon.