Terraforming - the megascale-engineering of a planet's surface to one more Earth-like - is now commonplace across the Solar System, and Pluto's is set to be the most ambitious transformation yet. Four billion miles from the Sun and two hundred degrees below zero, what this worldlet needs is light and heat. Through captured asteroids and solar mirrors, humanity's finest scientists and engineers are set to deliver them. What nobody factored in was a saboteur - but who, and why? From the start, terraformer Lucian is intrigued by nine-year-old Nou, silent since a horrifying incident that shook the base and upended her family into chaos. If he could reach her, perhaps he could understand what happened that day - and what she knows about the secrets of Pluto. Nou possesses unspoken knowledge that could put a stop to the terraforming. Gripped by her fears, unable to trust her family, there is no one she can talk to. Only through Lucian's gentle friendship will she start to rediscover her voice - and what she has to say could transform our understanding of the Universe.