It is the 31st century. A group of super heroes called the Legion of Super Heroes travel back in time to recruit earth's greatest super hero, Superman, to help fight the evil of their time. While their intentions were good, good intentions don't always produce good results. Instead of bringing back Superman, they retrieve a young Clark Kent from his farm in Smallville to the future.

The Legion must turn to help from their greatest foes when they are unable to stop the Sun-Eater themselves. Meanwhile, Superman confronts the Sun-Eater's controller but even he may be powerless before the alien.