Challengers of the Unknown (1958 DC 1st Series) #75
"Ultivac is Loose" Corinna Stark listens to the Challengers tell the story of their battle with Ultivac. Mostly a reprint of "Ultivac is Loose" from Showcase #7. Script by Denny O'Neil, art by George Tuska. Cover by Tuska, Jack Kirby, and Marvin Stein.