Comic Title: Challengers of the Unknown #18
Publisher: DC (National Comics Publications, Inc.)
Address: 575 Lexington Avenue, New York, NY
Cover Date: Feb/Mar 1961
On Sale Date: December 13, 1960 Newsstand Date December 13, 1960
Source: House Ad, Blackhawk #157, Page 20

Copyright Date December 13, 1960
Source: Library of Congress, Periodicals 1960

Frequency: Bi-monthly
Cover Price: $0.10
Page Count: 32
Circulation: 228000
Editor: Jack Schiff

Title: "The Menace of Mystery Island"
Pages: 13

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

Artist: Bob Brown

Reprinted In:
Showcase Presents:Challengers of the Unknown Vol. 2 TPB (2008)

Feature Character(s)

• Challengers of the Unknown (last appearance in Challengers of the Unknown #17; next appearance in Challengers of the Unknown #18)
• Ace Morgan (last appearance in Challengers of the Unknown #17; next appearance in Challengers of the Unknown #18)
• Rocky Davis (last appearance in Challengers of the Unknown #17; next appearance in Challengers of the Unknown #18)
• Red Ryan (last appearance in Challengers of the Unknown #17; next appearance in Challengers of the Unknown #18)
• Prof. Haley (last appearance in Challengers of the Unknown #17; next appearance in Challengers of the Unknown #18)

Supporting Character(s)

• June Robbins (last appearance in Challengers of the Unknown #17; next appearance in Challengers of the Unknown #19)
• Cosmo (the Challengers’ pet; next appearance in Challengers of the Unknown #21)

Villain(s)

• Several underworld criminals (no further appearances)

Synopsis:
June inherits a tropical island from her uncle. On the way to visit the island she and the Challengers intercept a small spacecraft. They rescue its sole occupant, an small orange creature. They name it Cosmo and take it on as a pet.

When the Challengers arrive on the island, strange events begin to occur. They split up which leads to Red and Prof being captured. The other Challs are soon caught as well, but Cosmo rescues them by chewing threw a net. Cosmo displays other abilities, such as force beams coming from his eyes.

The Challs discover that the island is being used by some criminals as an underworld supply depot. The crooks get the jump on them, but Cosmo rescues them again. The Challs finish off the crooks and turn them over to the authorities.