Prince Ardwin, known as Birdwing, the youngest of six brothers turned into swans by their stepmother, is unable to complete the transformation back into human form, so he undertakes a journey to discover whether his feathered arm will be a curse or a blessing to him.

Red-haired Marvin is convinced that the reason he looks different from the rest of his family is that he is really the lost prince of Shampoon.

In an alternate 1914 Europe, Austrian Prince Alek, forms an alliance with Deryn, disguised as a boy to loin the British Air Service, is learning to fly genetically-engineered beasts.