Dr. Shamon uses a gigantic magnetic "U" to draw a solid gold meteorite to the Earth. However, he is unaware of the fact that his "sky-mining" technique has released some exotic gases from the space cloud, which, when united with the oxygen in Earth's atmosphere, form a green mist and a red mist which can enlarge or shrink animals and plants except for humans.
While enjoying a day off with Firestorm, Cyborg is captured by the robot minions of supercomputer Brainiac, who intends to use the bionic dogooder for one of his typically evil "mind-blowing" experiments. To save the life of his fellow Galactic Guardian, Firestorm enlists the aid of Superman and rushes to Cyborg's rescue.—Mark Fair