Three new graduates from the H.I.V.E. Academy, Gizmo, Jinx, and Mammoth, are hired by Slade to ambush the Titans. The Titans try to stop them, but Robin is lost during the fight and Titans Tower is taken over by the H.I.V.E. students.
When a mysterious alien probe comes to haul Starfire away, sweet-natured Star has no idea why it came. And when Starfire's sister Blackfire stops by to visit, Starfire just wishes she would leave. Blackfire's wild, cool, and hip-- everything Starfire's not. The other Titans seem to like Blackfire so much, Starfire thinks they won't need her around anymore.
Cinderblock breaks into prison--and the Teen Titans arrive in time to stop a jailbreak. But when Robin and Cyborg's big “sonic boom” maneuver goes awry, the bad guy gets away--and the boys blame each other.
Dark ominous clouds blow in from the east, bringing Thunder and Lightning with them--two forces of nature made flesh in the form of costumed superteens. The stormy brothers aren't evil; they're just looking for a good time.
While playing in the park Cyborg suddenly shuts down. After rebooting he tells the other Titans that his batteries are dying. During a battle with Mumbo, Cyborg's emergency batteries die and he is lost. The Titans believe Mumbo to have kidnapped him, but he has instead been found by a strange man called Fixit.
Raven's creepy tantrum of crackling black energy leaves Dr. Light begging for mercy, and the Titans see a new side of Raven, her temper. But, when Cyborg and Beast Boy find a Mysterious Mirror in Raven's room, they're suddenly transported to a strange nightmare world that's somehow connected to Raven.
Starfire and Raven don't really "get each other." Star doesn't understand Raven's repression, and Raven can't deal with Starfire's emotional outbursts. But when The Puppet King imprisons Robin, Cyborg, and Beast Boy inside wooden puppets and takes control of the boys' bodies. The girls are going to have to understand each other -- if they want to survive.
A mysterious new villain called Trident appears and starts stealing nuclear waste from ships. The Titans go to investigate and meet a new hero, Aqualad. This new hero causes Beast Boy to become very competitive.
A thief called Red X, who knows the Titans’ every weakness, shows up. Every time the Titans try to catch him, they are badly defeated. Meanwhile, Robin - who has been obsessed with capturing Slade - isolates himself more and more from the team.
The Titans awake to find themselves captured as prisoners of Mad Mod, a madcap bad guy in a psychedelic suit. Mad Mod has decided to teach the teens a lesson, creating a massive mind-bending school full of optical illusions and brain-washing hypno-screens. Will the Titans be "re-educated" and lose their minds in the process?
Slade threatens to use a chronoton detonator, a device which can destroy the entire city if triggered. While Robin goes after Slade, the other Titans try to disarm the detonator. But then it turns out that Slade has other aims in mind than the destruction of the city.
The Titans can’t find a trace of Robin and start getting worried - that is, until they catch him red handed robbing a facility as Slade’s apprentice. After being defeated by Robin, the Titans are sure he has become a criminal. In truth, the life of a villain comes at an even more bitter price for Robin himself.
Cyborg has finally finished his 'baby', the T-Car. But after a battle with Overload his car disappears. It successively ends up in the hands of two bad guys called Cash and Sammy, then Gizmo, and finally Overload, the last of which forces Cyborg to make a painful decision.
