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. When his wife Jean and Hawkman attempt to help him, he flies into a rage, becomes the Atom and vanishes into an unexplored subatomic 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.
The Atom plunges uncontrollably through the microcosmos, his identity lost to him. The Hawkman holds a meeting, with the Justice League of America, aboard their satellite headquarters. Upon being reunited with his wife, Shayera, the Hawkman reached out to physicist, Ray Palmer, to share the good news. Palmer's wife, Jean Loring, informed the Hawkman of Palmer's increasingly erratic behavior. After bidding Shayera farewell, the Hawkman flew to Ivy Town, to investigate the situation. The Hawkman confronted Palmer, but his offer of assistance was met with violence. Palmer fled from the Hawkman, as the Atom.
The Hawkman, with Loring, journeyed to Palmer's laboratory, at Ivy University. En route, Loring spoke of Palmer's losing credit on research, when a fellow scientist, quite innocently, published the very theories and conclusions Palmer had. Instead of sharing credit, Palmer threw himself into his research, on the hunt for another breakthrough. Loring feared that Palmer was on the verge of a nervous breakdown, not unlike the kind she had suffered from, years prior. The Hawkman and Loring, confronted the Atom. Laughing maniacally, the Atom activated an incredibly advanced piece of technology, and vanished.
Upon further investigation, the Hawkman determined that the Atom had entered into the microcosmos. The Justice League of America beam down to Ivy Town, to begin their investigation into the Atom's disappearance. The Batman discovers that the Atom's machine is set for a predetermined destination. The Justice League of America uses the Atom's device to enter into the microcosmos. So traumatic is the experience that the Justice League of America immediately loses all sense of their individual selves, succumbing to amnesia.
Despite the sudden memory loss, the team comes together, to aid each other in surviving the perils of their journey, until they finally arrive on a strange new world. Unbeknownst to the Justice League of America, they are under observation. Each member has a vague recollection that they are seeking the Atom. When the Black Canary draws the Atom's symbol in the sand, the figure watching them makes her presence known. The woman refers to herself simply as "The Wanderer". The Atom's symbol is also the symbol of Goltha, a ruthless tyrant who rules the city of Ch'Anar, in the land of L'arra-Sha.
No sooner has the Wanderer given the Justice League of America this information then they are attacked by Goltha's Devil Guard. The Justice League of America, with the Wanderer, repel the attack of Goltha's Devil Guard. The Wanderer leads the Justice League of America into Ch'Anar. En route, both the Batman, and the Hawkman, take note of a series of hieroglyphics, though neither man can discern why the writing is familiar to him. The Wanderer uses the power of her staff to gain access to the city. The Justice League of America see the Atom's symbol adorning Goltha's citadel. Little do they suspect that the Atom is within the citadel, grown to monstrous size, and bound by the city's guards.
Note: Hawkwoman cameo as Shayera.