Adventure Comics #409

Adventure Comics #409 (On Sale: June 29, 1971), has a Supergirl cover by Dick Giordano. This is the only cover of Mike Sekowsky's editorial reign that was not penciled by him. As we will see, he really did not edit this issue despite what the indicia says.

We begin with Supergirl in "Invasion of the Mer-Men Part II" written and penciled by Mike Sekowsky and inked by Dick Giordano. Continuing from the last issue, Supergirl looks underwater for her co-worker Johnny and her captors, the whole time blaming herself for her co-worker's demise. Finally, she finds the secret base of the Mer-Men and discovers they are loading giant "tanker" space-globes with water to be shipped to their home planet.

In the meantime, a coalition of Earth armies launches attack after attack to destroy the globes, but they have force-fields that resist any attempt Earth makes to destroy them. Supergirl locates Johnny as a patrol of Mer-Men attacks her and she lets herself be captured. Once inside the base, she rescues Johnny, gets him out of the water, and then comes back to smash the globes herself, letting them rain their waters back on Earth.

The Mer-Men leader gives up, telling Supergirl that they couldn't load enough water up in time to save his world, anyway. He and the other Mer-Men depart resigned to their eventual extinction. Realizing this, Supergirl cries.

Next is a story already showing the new direction for Supergirl. "Fight with Fire Drake" is by E. Nelson Bridwell, Artie Saaf, and Dick Giordano. Mr. Stanton, the owner of KSF-TV, is throwing a party on his yacht. Freddy Nero, a party-crasher, tries romancing Linda Danvers, much to Geoff's disgust and jealousy. Minutes later, a scuba-costumed, masked villain called Fire Drake, who "breathes fire" with an acetylene torch nosepiece, loots the yacht and its passengers with his gang. Linda changes clothes and attacks the thieves. Supergirl tries to follow them when they run away, but her powers fail and she is repelled by Fire Drake's flame. 

That night Supergirl's mother, Allura, pays her daughter a visit and both women head to Kandor, where Linda's father Zor-El has some new power-substitution gimmicks for her: a bracelet which can enhance her normal strength when she is depowered, replacing the exo-skeleta cyborg, and her Legion of Super-Heroes flight-ring, to replace her jet-boots.

With her new mechanical powers, Supergirl encounters Fire Drake a second time, captures him, and unmasks him as Freddy Nero.

Our reprint is the Legion of Super-Heroes in  "The Condemned Legionnaires" by Edmond Hamilton, Curt Swan, George Klein, and Sheldon Moldoff and reprinted from Adventure Comics #313 (1963). When most of the female members of the Legion of Super-Heroes (and Night Girl of the Legion of Substitute Heroes) come down with the Crimson Virus, they have to be sent to a quarantine planet. The rest of the female members are hunted down by a mysterious masked villain named Satan Girl, who seems to be infecting the female Legionnaires with the virus.

With the arrival of Supergirl, who is immune to the virus, the male Legion members try to learn the origins of Satan Girl. When she proves immune to Kryptonite, Lead, and an anti-android weapon, the heroes are puzzled to figure out her true identity. Unable to defeat her due to her superior powers, Supergirl has the Legion go and collect the Legion of Super-Pets, as Satan Girl's powers would not affect them. The Super-Pets manage to easily defeat Satan Girl, who is unmasked, revealing that she is really -- Supergirl!? The weakened Satan Girl explains that she is the product of Red Kryptonite, which Supergirl was exposed to upon entering the 30th Century. Knowing that she had only 48 hours of life, she adopted the guise of Satan Girl and created a device that would siphon the Red Kryptonite radiation and infect females with it, in hopes that once she had rid herself of the Red Kryptonite energies she could live past the 48 hour period which Red Kryptonite effects.

With her plan a failure, and the 48 hours running their course, Satan Girl merges with Supergirl. Afterward, the Legion learns that Satan Girl managed to handle Green Kryptonite because she wore a lead suit. After this revelation, although they are victorious and their female members restored to normal, the Legion takes a moment to feel pity for Satan Girl, for all she wanted to do was live.  

Though this book says it is edited by Mike Sekowsky, the internal DC Job Numbers show that only the first story has the  "M-" prefix that designated Mike Sekowsky. The rest of the book, including the cover has a "J-" signifying Joe Orlando who supposedly takes over next issue.