Zhang lives in paradise, thanks to a household appliance: the fabricator. The fabricator prints whatever his heart desires, from frankfurters to foie gras, rubbers to rubber ducks, cocaine to chemotherapy. The miraculous device has banished homelessness and poverty to the dark ages. Fueled by alien trees from the other side of the wormhole, Zhang, like the rest of humanity, doesn't care how the fabricator works so long as it does.
But when he's sent through the wormhole on a rote journalistic assignment, he accidentally discovers a much bigger story. The fabricator is fueled by more than trees. His discovery sickens him; the cost of Earth's utopia is too high.
Atlas, the commandant of the other side, can't let Zhang go home to Earth. No one would use the fabricator if they knew its true nature. Billions of people, including his young daughter, depend on the fabricator for their medical treatments, for shelter, for food. If Zhang dies, the secret is safe. If he escapes, he digs paradise's grave.