Divide and Conquer is the 3rd aired episode (1st produced episode) of Teen Titans.
After a battle with Cinderblock, Robin and Cyborg get into a fight causing Cyborg to leave the team. Meanwhile, Slade causes trouble by releasing an evil monster named Plasmus.
The Teen Titans are alerted of a break-in to prison by the villain Cinderblock. The Titans arrive there quickly and begin fighting with Cinderblock, although they get beaten quickly. A maneuver by Robin and Cyborg called "The Sonic Boom", intended to stop Cinderblock from escaping, fails when they trip and get tangled in each other. As a result, Robin and Cyborg begin arguing with each other scaring the others including Raven. Cyborg, letting his jealousy and rage take over, decides to quit the team because he is tired of Robin always being leader and blaming others for his mistakes. Meanwhile, while they are arguing, Cinderblock punches through the walls of the prison, freeing some of the prisoners eventually reaching a high security room. Cinderblock reaches in and grabs a stasis with a sleeping person in it before escaping into the night while the Titans rally the other prisoners back to jail.
The next day, the Titans are discussing what had just transpired that night. Beast Boy believes that Cyborg should not have gone complaining about it to Robin and even tries calling Cyborg, but nobody picks up. Robin does not care about this at first, although he gradually resents it as he is forced to do all of Cyborg's chores as well as having nobody to play video games with. Even Raven is saddened about Cyborg's departure (though she won't admit it). At Slade's hideout Cinderblock emerges with the stasis tank on his shoulders. Slade congratulates him on his work and then wakes up the sleeping man inside. The man gasps and tells Slade that he shouldn't be awake and begs him to put him back to sleep. Slade remarks "I don't need you. I need PLASMUS!" and straight away the man in the tank begins to transform, breaking the tank and emerging as a gigantic purple monster. Slade then orders Plasmus to consume more toxic sewage at a waste management plant.
The Teen Titans hear about Plasmus's activities and rush to the waste plant, only to witness Plasmus growing bigger with the more waste he eats. The Titans begin to attack him with all sorts of attacks, but they fail as Plasmus regenerates his body and retaliates by attacking them with sludge. During this time the Titans receive a message about Cinderblock attacking another part of town. Robin insists that the rest of the Titans go while he holds off Plasmus. Starfire refuses and so do the rest of the team, knowing Robin cannot defeat Plasmus on his own. Raven, Beast Boy and Starfire begin attacking and manage to weaken and seperate Plasmus into smaller creatures, although they get trapped and consumed in Plasmus's parts in the process. Robin falls onto a conveyer belt and fights with one of Plasmus's sludge crabs. He is about to drop into a huge barrel of acidic ooze when Cyborg suddenly appears and grabs his arm, repeating his phrase "I've still got the Sonic if you've still got the Boom". Together they get up and attack Plasmus, who is already reduced to a small sludge monster due to the attacks of the other three Titans. Their Sonic Boom attack, consisting of Cyborg's Sonic Cannon and Robin's explosive disk, destroys Plasmus and returns him back to his human form: a man sleeping on the floor. Cyborg and Robin apologize for their earlier disagreements and agree to become friends again. Robin claims they failed in capturing Cinderblock, but Cyborg just laughs and points at the road, where Cinderblock is being tied up to a truck. He tells Robin he had already defeated Cinderblock and had wanted to show Robin as a peace offering. The episode ends with Robin suspecting someone is behind all these attacks and Cyborg assures that no matter who he is, he is no match for the Teen Titans.
Back in his lair, Slade smashes down his fist in anger, swearing that "next time my plans will succeed, and the Titans will pay!!"