Raised by woodtrolls in the Deepwoods all his life, Twig believes he is one of them, yet strongly suspects there is something different about him, as he does not fit in with them; in particular, he feels a longing to live as a sky pirate.

His adoptive mother tells him to travel to their cousin's house to mull things over, but during Twig's journey through the Deepwoods, he ends up unintentionally straying from the path.

Twig has a run-in with a skullpelt, a predator which hunts people who fall under the illusions of the Deepwoods' lullabee trees, but is saved by a caterbird which has just hatched from its cocoon.

The caterbird tells Twig his destiny lies "beyond the Deepwoods" and flies off, promising to return when he is in danger.

After a gyle goblin guides him to safety, Twig meets an injured banderbear, one of the forest's dominant predators.

Finally reunited with his true father, who apologizes for leaving him and promises to always protect him, Twig and the sky pirates set sail.

PublishersWeekly said, "The narrative will cast a spell over readers from the beginning with its utterly odd, off-kilter sense of logic and a vocabulary that is equal parts Dr. Seuss and Lewis Carroll";[6] Kirkus Reviews said, "Good fun, though the supporting cast tends to overshadow the plot.