[Book I of the Rittenhouse Saga] Centuries after most of humanity died out, a new civilization is slowly constructed upon the remnants of the old. Emery, a young man living in the walled city of Rittenhouse, has taken it upon himself to rescue "mutts," as the citizens of Rittenhouse call the impoverished masses outside. When Timothy, a boy afflicted with a fatal illness, seeks Emery's help, the two embark on a deadly errand to secure the medicine Timothy needs. This mission takes them from the safety of Rittenhouse into the wasteland outside it, where ancient superstitions are reborn and humanity struggles to survive amidst the ruins of a fallen American metropolis.

In the depths of winter, Emery is digging. Two months after the conclusion of Mutt, he is building an underground highway into the walled city of Rittenhouse to smuggle food and medicine to those living in the wasteland outside. When the gateman Green comes to him with news of a secret shipment and plans to intercept it, Emery sees a chance at redemption for his past failings. But as the search pulls him into a broadening web of conspiracy, his closest friends worry he is in too deep, determined find the shipment—or lose everything.