Legion of Super-Heroes in the 31st Century #10
an issue of Legion of Super-Heroes in the 31st Century by DC Comics
Issue description
An ancient legacy catches up with Brainiac 5 when he learns the terrible secret of his great-great-grandfather, Brainiac 1…one of Superman’s greatest enemies! To make it up to Superman, Brainy takes him on a trip to his home planet’s past — but an unexpected detour to the Phantom Zone could mean disaster!