Aquaman, the Atom, and the Elongated Man travel the high seas. The Atom discusses his desire to retire his costumed identity. Suddenly, the trio of heroes are struck by weapons' fire. An aerial battle between two space craft erupts in the skies above the Atlantic Ocean. One of the craft is downed, and crashes into the sea. Aquaman swims after the downed craft. A distress signal from the Justice League of America is sounded. Involved in their own case, Aquaman, the Atom, and the Elongated Man choose not to respond. Aquaman telepathically summons sperm whales, commanding them to keep the space craft afloat.
Aquaman boards the space craft, and discovers a single alien pilot, a woman who calls herself "Willow". Aquaman returns to his teammates with Willow. On the run from something called the Construct, Willow seeks asylum in Atlantis. Cannon 22 reports it's success to the Construct. The Construct orders Cannon One to fire on Cannon 22. The Construct knows that Willow has survived Cannon 22's attack. The Construct reveals it's genesis. Cannon 22 is destroyed for it's failure. Aquaman requests King Vulko, of Atlantis, grant Willow temporary asylum. In the war room, the Justice League of America interrogate Willow, who provides no answers.
The Construct makes contact with the Justice League of America, and Willow. The Construct issues an ultimatum, turn Willow over to the Construct in one hour, or the Construct will murder the entire population of Miami, Florida. The Atom activates his Justice League of America distress signal, unaware that the rest of the team is involved in a conflict with the Manhunters. Willow requests that the Atom be assigned to her for protection, while Aquaman, and the Elongated Man, deal with the crisis in Miami. The Atom expresses uncertainty that he is the best choice to protect Willow, believing his powers to be wanting.
Forced to surface, to refill the air tanks on their Atlantean craft, the Atom, and Willow, are attacked by Cannons. The Atom leaps to Willow's defense, but is quickly subdued. Willow, however, doesn't actually require the Atom's protection. Willow, using her heretofore unknown martial arts prowess, destroys the Cannons. The Atom is outraged that Willow would conceal such abilities from him. In his fury, the Atom questions why Willow even bothered to ask him to protect her. Aquaman, and the Elongated Man, arrive in Miami, to find the population evacuating in a panic. The Cannons have activated the Thanotron, a machine that is slowly killing the populace.
The Elongated Man spots two Cannons, on guard, outside of a downtown hotel. Aquaman, and the Elongated Man, storm the hotel. Aquaman battles a horde of Cannons, while the Elongated Man begins searching the hotel floors for the Thanotron. The Elongated Man finds the Thanotron, on the roof of the hotel. The Elongated Man tricks the Cannons into destroying the Thantotron. The Construct seems unconcerned with the heroes victory in Miami. One of the Cannons takes issue with the Construct's callous disregard for it's fellow Cannons. The Construct sets the Cannon straight on the Construct's superiority.
With the Manhunter case closed, the Justice League of America address their growing concern over the absence of Aquaman, the Atom, and the Elongated Man. With the Justice League of America exhausted after their ordeal with the Manhunters, Superman decides that only he, and Wonder Woman, are required for the investigation. Wonder Woman bristles at being denied rest, with the other members, but complies. The Flash, and the Green Arrow, ask to speak to Superman alone. The Green Arrow calls for Wonder Woman's dismissal from the team, citing her hostile demeanor towards him, and the Flash.
Superman agrees to speak with Wonder Woman, but fears that the entire Justice League of America is beginning to fall apart. The Construct manifests itself, in a body built of rock and sand, on the island the Atom, and Willow, are hiding on.The Construct strikes the Atom, and Willow, down. The Atom attacks the Construct, to no avail. Willow suggests the Atom switch tactics. The Atom shrinks down to sub-atomic size, and enters the Construct. The Atom begins to enlarge, causing the Construct to expand, and then explode. The Atom finally realizes why Willow selected him to protect her. Only the Atom could have defeated the Construct. Willow reveals a few details of her past.
After an extended period in the far reaches of outer space, Willow has returned home, to Earth, to give birth to her child. Willow states that her child is destined to bring new life into the universe, as he leads mankind to the stars. As their are many in the universe, like the Construct, who wish to stop that from happening, Willow must raise her child, and live out the rest of her days, in hiding. The Atom agrees to keep Willow's secrets. Superman, and Wonder Woman, return to the satellite headquarters of the Justice League of America, with Aquaman, and the Elongated Man. Moments later, the Atom beams up to the satellite. Whatever questions the Justice League of America has for him, the Atom offers no answers.
"100 Issues Ago In... Justice League of America" reprints material from Justice League of America #42 (February, 1966). A plot summary for that story can be found at the link.
- Brief origin of the Manhunters.
- This issue contains the Hostess Superhero Ad, The Joker as "The Cornered Clown".