Ever since Prue McKeel returned home from the Impassable Wilderness after rescuing her brother, life has been pretty dull.

School holds no interest for her, and her new science teacher keeps getting on her case about her dismal test scores and daydreaming in class. Her mind is constantly returning to the verdant groves and sky-tall trees of Wildwood, where her friend Curtis still remains as a bandit-in-training.

But all is not well in that world. A hard winter has come and discord reigns in the wake of the so-called Bicycle Coup. Dark assassins with mysterious motives conspire to settle the scores of an unknown client. A titan of industry employs inmates from his orphanage to work in his machine shop, all the while obsessing over the exploitation of the Impassable Wilderness.

Under a growing threat, Prue is drawn back into Wildwood, where she and Curtis will face their greatest challenge yet: to save themselves and the lives of their friends, and to bring unity to a divided country. But in order to do that, they must go under Wildwood.