From the 30th century, three members of the Legion of Super-Heroes travel back in time to stop Brainiac from killing Clark Kent in his youth.
Did You Know?
Smallville featured a similar story (three Legionnaires go back in time to help a young Clark Kent fight off Brainiac) in the season eight episode "Legion" (written by Geoff Johns). "Legion" featured Saturn Girl, Cosmic Boy, and Lightning Lad (who replaced Chameleon Boy in the animated series' version, possibly because at the time of the show's production Lightning Lad's early-1990s' character was Live Wire, which might have been confused with the original antagonist created for "Livewire" two seasons before.). See more
[Three members of the Legion of Superheroes confronts Brainiac
Chameleon Boy. Cosmic Boy. Saturn Girl. Where are the other Legionnaires?
Hey, it's only you.
References Superman II