At Roanoke Island, Klarion the Witch Boy goes to a crossroads and uses a crystal to cast a magic spell. He then summons his fellow mages Wotan, Blackbriar Thorn, Felix Faust, and the Wizard, and together they begin a powerful incantation. At Mount Justice, Miss Martian and Superboy return with groceries. Zatanna comes to visit and Artemis wonders if she's joining the team, but Zatanna admits that her father is too over-protective to let her. Suddenly Batman, Zatara, and Red Tornado disappear while mystic chanting fills the chamber.
At Roanoke, the other adult mages disappear as Klarion smiles in triumph.
At Fawcett City, Billy Batson, Captain Marvel's alter-ego, is in his apartment when his Uncle Dudley suddenly disappears. He assumes it's an enemy attack and prepares to summon Captain Marvel, but then notices that the announcer on the news has disappeared as well. When Billy looks outside, he sees that all of the adults in the neighborhood have disappeared, leaving frightened children. Billy realizes that if he transforms into Captain Marvel, he could disappear as well and refrains from using his magic word.
Young Justice sets up a refugee at the local high school and discovers that all the adult heroes have disappeared. Kids throughout the world are posting that every individual 18 or older has disappeared. Zatanna warns that the magic required to cast a spell would be incredible and Robin says that they need her to track down the spellcaster. He brings up footage of Zatara using a spell to locate the Injustice League, but she warns that it takes more than just knowing the words. Robin assures her that she can do it and that they'll bring everyone back.
In Happy Harbor, Superboy conducts emergency relief efforts for the children stranded when their parents disappeared, while Artemis entertains children at the high school gym. Kid Flash refuses to go to his empty home since his parents disappeared with the other adults.
In Fawcett City, Billy makes his way to the Justice League transporter but discovers that it is only programmed to recognize Captain Marvel, not him. As he leaves, Aqualad broadcasts a worldwide transmission to ask all of the children to step up and take care of the younger ones who can't take care of themselves. Billy goes to the airport and asks a teenage girl, Amber, there if she can fly a plane.
Kid Flash goes to the trophy room and contemplates the Helm of Fate. Aqualad comes in to tell him that the adults have disappeared from Atlantis as well, and Kid Flash wonders if they're desperate enough to don the Helm. His leader reminds him that Nabu can permanently possess anyone who takes it. Zatanna comes in to tell them that she's ready to use Zatara's locator spell. The group assembles and Zatanna casts the spell, which reveals Roanoke as the source of the magic.
Amber gets the plane in the air and they fly to Happy Harbor. However, they arrive at midnight just as Amber tells Billy that she's turning 18. She disappears from the plane and Billy realizes that he'll have to land the plane on his own.
Klarion casts his spell and disappears.
At Mount Justice, Miss Martian and Superboy return with groceries. Zatanna comes to visit and Batman wonders if Zatara will be letting his daughter join the team. He's reluctant to let her join because he's too over-protective. Suddenly Zatanna and Young Justice disappear while mystic chanting fills the chamber.
Children throughout the world disappear and adults begin to panic. A mob swarms STAR Lab, demanding answers and blaming the scientists. Meanwhile, Sportsmaster in his civilian guise aggravates the mob and a non-costumed Riddler uses the opportunity to slip into STAR Labs and steal something.
Zatara goes to the trophy room and contemplates the Helm of Dr. Fate. Batman comes in to tell him that the League is handling the emergencies and that only he, Red Tornado, and Zatara are available to travel to Roanoke, which Zatara has pinpointed as the source of the magic. They figure that they're not desperate enough for Zatara to try using the Helm of Nabu. Batman notes that Captain Marvel has gone missing.
Billy realizes he has no choice but to speak the word and does so. He suddenly finds himself in mid-air. He hears Amber screaming and realizes that she's falling to her death. Once he catches her, Captain Marvel flies to Mount Justice and is glad to see that Batman and Zatara are back. They realize that there are two dimensions, one for adults and one for children, and Captain Marvel can travel between them. He says "Shazam!", transforms into Billy, and finds himself in the dimension with Young Justice. Billy has Miss Martian read his mind to confirm he's telling the truth, but Kid Flash isn't convinced until Billy Batson tells him some of the things he's been doing for the speedster.
Using Billy/Captain Marvel as a courier, the two teams in the two dimensions coordinate their attack on Roanoke Island. They assume that the two dimensions will merge naturally once the magic-user is defeated.
Young Justice starts their assault on Klarion, who deflects their initial onslaught. The others launch a new attack but Klarion easily stops them. Kid Flash suggests that they attack his cat Teekl and Artemis opens fire, but Klarion transforms her arrow and Teekl transforms into a giant cat-creature.
Batman, Zatara, Red Tornado, and Captain Marvel attack the adult villains and Zatara manages to stun them with lightning.
Klarion realizes that his adult allies have been attacked and unleashes magical lightning from the crystal at the heart of his incantation. Realizing that they're outmatched, Zatanna summons the Helm of Fate.
Zatara realizes that the crystal is at the heart of the incantation. He tells Captain Marvel, who transforms into Billy and tells Miss Martian what they need to do. When Zatanna hears, she dons the Helm, ignoring the warnings of the others. She transforms into Dr. Fate and prepares an assault on Klarion, while Miss Martian tells Billy to transform and inform Zatara of what has happened.
When Zatara learns what his daughter has done, he tells Captain Marvel to go back and stop her. He refuses, saying that they need to end the battle quickly so they can help Zatanna. Captain Marvel has an idea and tells the adult heroes to distract the villains while he carries out his plan.
Dr. Fate continues his assault while Young Justice regroups and assaults the force bubble that Klarion is using to protect himself. Dr. Fate starts to waver and transform back into Zatanna, and Klarion boasts that with the worlds divided, Nabu is divided as well. Nabu refuses to accept Zatanna's sacrifice and continues his assault, and the youths' combined efforts bring down the force field. Kid Flash runs in and grabs the crystal, and tosses it to Dr. Fate.
Captain Marvel bores beneath the earth, comes up within the magic circle, grabs the crystal, and throws it to Zatanna. He casts the same spell as Dr. Fate, remerging the two worlds. Klarion escapes with Teekl, disappearing through a magical portal. Dr. Fate refuses to stop him, noting that Klarion can't be contained. Zatara calls upon Nabu to release Zatanna, but Dr. Fate insists that the world needs him, and has released Kent Nelson's spirit to prevent any internal debate. Zatara offers himself, saying he is a better candidate, and gives his world that he will don the helmet once Nabu removes it from Zatanna. Nabu agrees and father and daughter are briefly reunited before Zatara dons the Helm of Fate. Batman promises him that that they'll take care of Zatanna for him. Zatara transforms into Dr. Fate and disappears with the magical villains, while Zatanna looks on in horror.
Later, Kid Flash returns home and is reunited with his mother and father.
Billy returns to Fawcett City and hugs Uncle Dudley.
Zatanna moves in to Mount Justice and the team promises to be there for her if she needs anything. Once she's alone, Zatanna breaks into tears.
Klarion contacts the Brain, who congratulates him on the chaos that he caused that allowed them to steal their prize on behalf of the Light. Sportsmaster and Riddler arrive with the specimen they stole from STAR Labs: a piece of the starfish alien.