The burning man on the cover of Super-Team Family 9 (Feb/March 1977) looks much better in Rich Buckler and Jack Abel's illustration than he does in the Skeates, Sherman and Abel Challengers of the Unknown story inside.
The Challengers of the Unknown head to a volcano to deal with a mad scientist, Chrislow. He had worked for the US military designing weapons, but went nuts thinking the world was getting too violent, and now plans to detonate massive bombs in a volcano, which will destroy the environment, and end all life on earth.
Ace Morgan, Red Ryan, Professor Haley and Rocky Davis descend into the volcano and find a bomb, bringing it back up and tossing it into the ocean. Rocky gets injured along the way, and they see a burning man, like the one on the cover, who tries to attack them but appears to fall to his death. Then Chrislow informs them that there is a bigger bomb, further down, so the team has to go back into the volcano, although Rocky stay behind this time.
The team lose their footing and fall, but a strange effect prevents this from being deadly, and they find a city deep inside the volcano.
The few survivors of an ancient race live there, protected by robots, such as the one the heroes encountered earlier on. The burning effect is actually protection against the heat of the volcano, and the Challengers get sprayed with the solution that will allow them to appear to burn as they climb back up. The people of that civilization have the bigger bomb, but are prepared to let it go off, destroying them, but shielding the rest of the world from the effects of the blast.
Kind of a meh story, as before I preferred the Doom Patrol reprint. There is also a Green Arrow reprint in this book, by Jack Kirby.