Batman meets with his fellow Batmen, the Batmen of All Nations, at their newly-refurbished headquarters. They admire the statues that Batman commissioned, only for Batman to point out that he didn’t commission any statues. The statue of Batman cracks open, revealing the face of Joker beneath. The Joker leaps out of one statue, as do the Jokers of All Nations. The two teams come together in titanic conflict, while Joker fires a flamethrower at Batman, destroying the meeting table. Batman blocks the nozzle with a Batarang and Joker is forced to discard the overheating weapon. A stray shot brings down the roof on the villains, while Batman delivers the final punch to Joker.
Captain Atom shows his new teammates in Justice League International the public service that he just made, concerning a warning about downed power lines. Aquaman and Martian Manhunter are unhappy with his arrogant attitude, while Captain Atom points out that the non-powered Batman has no place in the JLI. The others object, but Captain Atom points out how easily any super-powered villain could defeat him and walks away. Batman explains that Captain Atom is Nathaniel Adams, a retired Air Force captain. He was atomized in an atomic experiment gone awry and gained energy superpowers.
Before they can pursue the matter, the JLI receives a trouble-alert that Major Force is on a rampage, attacking the Pentagon. Captain Atom has fought the villain before and is eager to prove himself. Meanwhile, Major Force rips apart the building looking for the Quantum Vacuum. Batman, Captain Atom, and Aquaman arrive and Captain Atom pushes aside Batman and insists on handling the villain himself. Batman refuses and tries to assist, and Major Force brings down Captain Atom and finds the Quantum Vacuum. He dons the device and fires a blast of energy at Captain Atom, bringing him to his knees in agony and draining his energy, reverting him to human form.
As Major Force prepares to deliver a final, lethal blast, Batman swings away with Nathaniel. The villain flies away and Batman contacts Martian Manhunter and orders him to have the rest of the JLI take on Major Force. When Nathaniel objects, Aquaman tells him to let the JLI handle the villain. They beam up to Watchtower and Martian Manhunter explains that the Quantum Vacuum is a prototype that allows the wearer to tap into any source of nuclear power. Nathaniel insists on helping, pointing out that Batman does fine without powers and he can do the same. However, he has trouble accepting his new limitations.
Major Force goes to a nuclear plant and absorbs the energy. When the other members of the JLI try to stop him, the villain easily defeats them. Aboard Watchtower, Nathaniel discovers that he’s unable to even open a jar of pickles. Batman tries to console him, but Nathaniel says that he feels like a total loser, just like Batman must. Disgusted, Batman starts to walk away but Nathaniel asks for his help in functioning as a non-powered hero. Batman puts him through the JLI training room and can’t help but take some satisfaction in the fact that Nathaniel is so easily smashed down. When Nathaniel is unable to muster a fight, Aquaman tries to inspire him but Nathaniel bemoans his fate as a powerless c-lister, and the Atlantean decides to sing an inspirational song on the value of heart.
Martian Manhunter interrupts to tell them that JLI have been defeated. Batman, Aquaman, and Martian Manhunter prepare to teleport down and Nathaniel insists on going with them. They refuse, saying that they need him to serve monitor duty, and teleport to where Major Force is attacking. Despite their teamwork and determination, the heroes are useless against him. Aboard Watchtower, Nathaniel watches and flies down to help.
As Major Force defeats Martian Manhunter, Nathaniel bails out of the plane after leaving it on a collision course with the villain. He parachutes down and Batman compliments him, but then Major Force encases both Batman and Aquaman in energy sheaths. Major Force grabs Nathaniel, who points out that the Quantum Vacuum has absorbed too much power. The device explodes, freeing the others and restoring Nathaniel’s powers. He delivers the final blows to Major Force, defeating the villain.
Later aboard Watchtower, Batman assures Captain Atom that he handled himself as a real hero. He assures them that he’s learned a valuable lesson, and is soon making public service announcements about how people without powers are fragile and pathetic.