Natuurkundeleraar Ryland Grace wakes up – light-years from home – on a spaceship without remembering who he is or how he got there. Gradually, his memory returns: he is on a mission to find out why a mysterious substance is causing the sun to fade. To save everything on Earth from extinction, he must rely on his scientific knowledge and a number of unorthodox ideas. But an unexpected friendship means he might not be entirely on his own.