"The Galactic Scourge!" by Molno/Colletta; 7 pages (5917).
"Introducing Captain Atom" by Ditko; 9 pages (5694).
Captain Allen Adam makes the last adjustments to a nuclear missile, readying it for a test detonation in space, but gets trapped inside. Rather than dying, he is transformed into Captain Atom, and puts himself in the service of his country.
Reprinted in Strange Suspense Stories (1955) #75.
"Venture in the Ventura" 2 pages, text only.
"The Captive World" by Molno; 7 pages (5947).