This issue of CHALLENGERS OF THE UNKNOWN reprints one of the stories from #2 and one from #1, from back in 1958. They look good, except for the fact that they insisted on re-colouring the Challs outfits from the plain purple to a red and yellow combination, and more distracting they colour them with gloves, which looks odd when you have the drawings clearly being of bare hands.
"The Monster Maker" is from #2, and features the Challs going up against a criminal who has gained mental powers to turn thoughts into reality. This is a good excuse for Kirby to draw a giant gorilla, a dragon, a giant horse-riding knight and more.
"The Human Pets" is from #1, and is a goofy story about the Challs being taken captive by a giant alien child. Silly but fun, with a neat looking alien, and some nice Kirby designs on the alien child's toys.
Marvin Stein inked both these stories, and does a great job. Very clean and crisp line.
Joe Kubert draws a new cover, based on the gorilla scene in the first story.