By the year 2213, Earth has been destroyed by the sun, which has started going supernova much sooner than scientists predicted. On Mars, the last humans scramble to prepare for a 150-year journey to the nearest star with possibly habitable planets--because Mars, too, is doomed. Liam Saunders-Chang and his friend Phoebe, are preparing to board the last starliner to depart, but before they do, they will make a series of discoveries about the nature of time and space itself that points to a more sinister cause for the sun's accelerated demise.