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.

Heroin addict Mark Renton stumbles through bad ideas and sobriety attempts with his unreliable friends --Sick Boy, Begbie, Spud and Tommy. He also has an underage girlfriend, Diane, along for the ride. After cleaning up and moving from Edinburgh to London, Mark finds he can't escape the life he left behind as Begbie and Sick Boy come knocking.