It is five years after NASA found liquid water on the surface of Mars. The Martian atmosphere has changed. All contact has been lost with the planet. On Earth, entrepreneur Michael Macmillan is preparing the first crewed mission to the Red Planet, with a seat reserved for an ordinary person willing to do something extraordinary. When Faye Banks secretly enters the Seat 25 competition, she never expects to win. But when the dangerous one-way trip becomes a reality, her life on Earth is turned upside down. With time running out, Faye must decide whether to leave her husband, family and friends, or has the prospect of leaving forever made her realise what she has here on Earth?