Black Beetle and Deathstroke enter a large cavern beneath Santa Prisca. After they both confirm that the area is secure, they usher in their respective groups, The Reach and The Light. Vandal Savage and the Ambassador greet each other, while Artemis, disguised as Tigress, whispers to Aqualad that they're in over their heads.
When The Ambassador wonders where the rest of The Light is, Vandal and Ra's Al Ghul inform them that they're busy handling damage control after recent revelations that The Reach has a hidden flight. The Ambassador angrily demands to know how the heroes gained access to the Bialyan scarab temple, and Aqualad steps forward to explain. He points out that The Light didn't know about the temple because The Reach never informed them that a scarab had reached Earth thousands of years ago and the native locals found a way to negate it. The Reach Scientist complains about how the Ambassador ignored her, but he silences her with a glance.
The Ambassador refuses to discuss the temple further, but the members of The Light point out that the aliens have failed repeatedly in their attempts to conquer Earth. Put on the defensive, the Ambassador tells them that they have summoned Black Beetle from the Warworld key chamber and plan to kill Green and Blue Beetle, take their scarabs, and put them on cooperative host bodies. When he reminds The Light that they are merely servants of a soon-to-be conquered planet, Black Manta insists that he is nobody's slave. Black Beetle attacks him and Artemis and Deathstroke attack Black Beetle. The Ambassador's soldiers return fire and a blast knock Artemis back into Ra's. As he helps her up, he notices something unusual about the charm on her neck.
Aqualad finally steps in and tells everyone to stop, reminding them that they have a common enemy in the Justice League and its sidekicks. The Ambassador convinces Black Beetle to stand down and Aqualad asks if the League members on Rimbor will return to Earth. Vandal assures Aqualad that he has bribed the jury to make sure that the League are convicted, and points out that the Reach treaty forbids the Green Lantern Corps from helping a planet that invites them in. The Ambassador boasts that his people can easily generate more half-lies to rebuild the population's trust in The Reach. Meanwhile, Ra's approaches Artemis, grabs her, and removes the charm from her necklace. As the gathered villains look on, Artemis' features revert to normal.
Vandal and the Ambassador quickly realize that if Artemis isn't dead at Aqualad's hands, then Aqualad has betrayed them. When Black Manta tries to stop Black Beetle from killing his son, Deathstroke shoots down Aqualad and Artemis. As Black Manta holds his dying son, Aqualad triggers a remote, activating a pre-recorded hologram. In it he tells The Reach that The League has been conspiring to betray them ever since they lured the aliens to Earth by sending the mind-controlled League to Rimbor. Since then, The Light has undermined all of The Reach's attempts to conquer Earth, giving Young Justice access to the temple and neutralizing the mind-control elements in the Reach's energy drink. Once the recording ends, a surprised Vandal admits that Aqualad is the first person in 50,000 years to disrupt his plans.
Furious, the Ambassador threatens to use Warworld to attack the traitorous Reach. Vandal tells him that his organization now has the crystal control key. Aqualad and Artemis stand up, no longer "dead." "Deathstroke" levitates his sword over to Vandal's throat and reveals that she's actually a shapeshifter Miss Martian. Her teammates enter the cavern and Vandal congratulates them... but warns that The Light is always prepared. The Brain glows, sealing off the cavern, and a hangar door in the roof opens. The Light's ninjas drop down and Vandal tells them to dispose of the heroes. However, three of the ninjas attack their teammates, revealing that they're Beast Boy, Blue Beetle, and Lagoon Boy in disguise. A fight breaks out between all three sides and Wonder Girl, Robin, and Impulse reveal that they also infiltrated the ninja force.
Vandal complains about the "children" and Aqualad points out that he keeps underestimating them. The immortal villain concedes the point and summons Klarion the Witch Boy. The sorcerer transforms Deathstroke's sword into a fire serpent and has it attack Miss Martian. As Klarion teleports Vandal away, Ra's tells both villain groups to stop fighting since the heroes have no jurisdiction there. Disgusted at his former allies' cowardice, Black Beetle stabs Ra's through the heart. Ra's bodyguard Ubu runs to his master's side, knocks aside Artemis, and uses a grapple gun to escape through the ceiling door. As the ninjas close in on Artemis, Kid Flash runs to his girlfriend's side to help her.
Furious, Black Manta confronts his son and demands to know how Aqualad could have betrayed him. Aqualad admits that he's seen his father's noble side but plans to fight him as long as he wastes his gifts on villainy. The villain launches an attack at his son, determined to teach him a lesson in ruthlessness.
Lagoon Boy destroys the fire serpent menacing his ex-girlfriend. She thanks him and they look at each for a moment, and then jump back into the fight.
As Kid Flash and Impulse run into battle, Kid Flash points out that he had hoped Impulse would succeed him since he plans to retire. Impulse is thrilled to hear it and disarms The Brain, but stunned when Mallah throws Beast Boy into him. Meanwhile, Aqualad finally knocks Black Manta unconscious.
As the Ambassador and the Scientist flee the cavern, Blue Beetle pins them to the wall before turning back to the main battle. Black Beetle informs the Ambassador that he is unfit and relieves him of duty under The Reach's Acquisition Code. He pulls the Scientist free, saying she could still prove useful, and flies out of the cavern. Meanwhile, the heroes have defeated the remaining forces. Aqualad worries that they've failed, letting some of the villains escape, but Nightwing assures him that they've won a major victory. Artemis recorded Vandal's words and they can use the evidence to clear the League.
On Warworld, Klarion teleports away The Reach's guards, while Vandal attacks League members Black Canary, Captain Marvel, and Black Lightning as they stand guard.
At Watchtower, Nightwing eagerly turns over command of Young Justice to Aqualad, the team's original leader. As they talk, a magical portal opens and Klarion throws the unconscious League members through. Nightwing and the others watch as Warworld powers up and leaves Earth's orbit.
Black Beetle and the Scientist watch as Captain Atom presents the evidence to the UN Assembly, which votes to withdraw The Reach's invitation. They realize that since they are no longer invited to Earth, the Green Lantern Corps are no longer bound to stay away and will soon be arriving. Black Beetle vows to destroy Earth to cover any evidence that The Reach interfered with the planet.