After a global catastrophe, the last man on Earth finds himself questioning his purpose and sanity as both his deceased wife and a mysterious stranger confront him with his past, his present, and whatever future might remain in the wastes of a dead world.

约翰·谢里登（John Sheridan）在穿越银河系寻找回家之路的途中，意外发现自己被传送穿越多个时间线和交错现实。在此过程中，他与一些熟悉的面孔重逢，同时揭示了关于宇宙的历史、目的和意义的宇宙新启示。