A team of superheroes from the 31st century heads back in time to enlist Superman's help in battling their nemeses, the Fatal Five. But when they arrive in the Man of Steel's hometown, Smallville, they discover that they've miscalculated a bit. Instead of a powerful, confident Superman, they find the introverted, insecure young adult Clark Kent, whose abilities need fine-tuning and who knows nothing of the legend that comic book history says he'll become.

It takes some effort, but Brainiac 5, Bouncing Boy, and Saturn Girl convince Clark that he's special and may be able to help them. Although he sincerely doubts that he's the "Superman" they keep talking about, his curiosity is piqued enough that he goes back to the future with them. The legion itself is a group of well-meaning, undisciplined and unpredictable, super powered young adults who just happen to be the Universe's only hope. The Legionnaires are still light-years away from becoming the seasoned (and cynical) pros of the Justice League.