Comic Title: Challengers of the Unknown #7
Publisher: DC (National Comics Publications, Inc.)
Address: 575 Lexington Avenue, New York, NY
Cover Date: Apr/May 1959
On Sale Date: February 17, 1959 Copyright Date February 17, 1959
Source: Library of Congress, Periodicals 1959

Frequency: Bi-monthly
Cover Price: $0.10
Page Count: 32
Editor: Jack Schiff

Title: "The Isle of No Return"
Pages: 12

Feature(s):
Challengers of the Unknown (of Earth-1)

Writer/Penciller: Jack Kirby
Inker: Wallace Wood

Reprinted In:
Challengers of the Unknown #78 (1973)
Challengers of the Unknown Archives Vol. 2 HC (2004)
Showcase Presents Challengers of the Unknown Vol. 1 TPB (2006)
Challengers of the Unknown Omnibus HC (2012)
Challengers of the Unknown by Jack Kirby TPB (2018)

Feature Character(s)

• Challengers of the Unknown (last appearance in Challengers of the Unknown #7; next appearance in Challengers of the Unknown #8)
• Ace Morgan (last appearance in Challengers of the Unknown #7; next appearance in Challengers of the Unknown #8)
• Rocky Davis (last appearance in Challengers of the Unknown #7; next appearance in Challengers of the Unknown #8)
• Red Ryan (last appearance in Challengers of the Unknown #7; next appearance in Challengers of the Unknown #8)
• Prof. Haley (last appearance in Challengers of the Unknown #7; next appearance in Challengers of the Unknown #8)

Supporting Character(s)

• June Robbins (last appearance in Challengers of the Unknown #6; next appearance in Challengers of the Unknown #8)

Villain(s)

• Anton Zammer and Nero (a criminal and his parrot; no further appearances)

Synopsis:
The Challengers track down a mysterious criminal with an invention that lets him walk through walls. The trail leads to a small island where the crook has a secet hide-out. When the Challs land on the island, the crook, Anton Zammer, captures them after using a shrinking ray to reduce their size. He reveals that the inventions were created by the late Professor Macon. Zammer offers the Challengers a look at Macon's final and greatest invention.

Meanwhile, June has stowed away in the Challengers helicopter. She sneaks into the lab and breaks the Challengers free before the new invention can be activated. The Challs restore themselves to normal size, then the new machine activates. The invention disables all the other inventions, leaving the Challs free to capture Zammer.