Science teacher Ryland Grace wakes up on a spaceship light years from home with no recollection of who he is or how he got there. As his memory returns, he begins to uncover his mission: solve the riddle of the mysterious substance causing the sun to die out. He must call on his scientific knowledge and unorthodox ideas to save everything on Earth from extinction.

Six months into a solo mission, a lonely astronaut confronts the cracks in his marriage with help from a mysterious creature he discovers on his ship.