Captain William D. Stanaforth is on a one-way mission to Mars, and though the entire world is watching him, he is completely alone in a dark and distant sea of stars. When an astronaut on a parallel mission encounters mechanical failure, Stanaforth risks everything to save her. As the two form an undeniably strong bond from their respective ships, the physical journey takes a toll on Stanaforth's life-sustaining systems, forcing him to make impossible choices.