Adventure Comics 1938 #409 - 2.0 - $2.50

After the female Legionnaires are struck by a mysterious Crimson Virus, Satan Girl wants to take their place. But when she attacks the girls, Supergirl tries to solve the mystery of who she is.

Satan Girl is defeated by the Super-Pets and revealed to be an evil Red Kryptonite duplicate of Supergirl.

On-sale date from copyright registration.

• Invasion of the Mer-Men! - Pencils formerly credited to Art Saaf based on an apparently unused cover, job #J1313, prepared for this issue.
• Fight with Fire Drake - Opening caption connects this story to the previous story.
• - Includes a letter from future comics writer and "DC Answer Man" Bob Rozakis.