Adventure Comics (1938) 378-A

Tales of the Legion of Super-Heroes in "Twelve Hours to Live!"
While the Legion is celebrating Brainiac 5's birthday, Brainiac 5 realizes that everyone's cup of kuno juice has been laced with a powerful poison. Brainiac 5 tells everyone they only have 12 hours to live unless he can come up with an antidote. While Brainiac 5 heads to his lab to attempt to create an antidote the rest of the team split up to spend their last hours. Superboy decides to spend his last remaining hours doing selfless acts for the galaxy. Duo Damsel spends time with her family. Karate Kid chases down the Fatal Five. And Projectra spends her time alone in Metropolis. As the Legionnaires return to their headquarters, Brainiac 5 tells them he has failed to come up with an antidote, just as the Legionnaires seemingly all drop dead. The killer then enters the headquarters laughing, then suddenly time seems to have been stopped.
(Story continues in the next issue.)