Two kids fight to save their city from eternal winter in this gripping fantasy by Newbery Medalist Avi, illustrated by three-time Sibert honouree Brian Floca.

The Kurbs give people light and warmth to establish a city, on one condition: The people must return the Power every year or risk losing the city — forever. This system works for centuries until evil Mr. Underton tries to steal the Power. If he succeeds, the Kurbs will take back the City, reducing it to a dark and frozen tundra. It's up to Carlos and Sarah to find the Power — housed in a subway token — and keep the City safe, despite secrets of Sarah's history that are entwined with the token. What ensues is a race against darkness. A race against the lies of the past. And most of all, a race against time