Justice League of America #213 Newsstand

INTO THE MICROCOSMOS! Crushed when another physicist unwittingly duplicates a research paper he had planned to give at the International Physical Year Symposium, Ray Palmer suffers a nervous breakdown and, when his wife Jean and Hawk-man attempt to help him, he flies into a rage, becomes the Atom, and vanishes into an unexplored sub-atomic world. Using a device of Ray's invention, the Justice League members follow him but lose their memories in the process. They encounter a woman called Wanderer, and are attacked by reptilian humanoids she calls Devil Guards, creatures of Goltha, the micro-world's tyrannical ruler. The heroes journey with her to the city of Ch'anar, unaware that the Atom, now a comparative giant in size, is a captive there.