Haunted is the 31st episode of the Teen Titans series and the fifth episode of the third season.
The episode begins at midnight, with Cyborg tiredly asking why Robin's still up. Without removing his gaze from the large crime computer's screen, Robin informs Cyborg that he still has work to do. Cyborg yawns and heads off to bed himself. Shortly thereafter, Robin heads to the basement of the tower. In the warehouse area of the basement, Robin opens a box full of Slade artifacts and removes Slade's mask. As dust falls from the mask, causing Robin to cough, Cyborg turns on the lights from behind him and informs him that Slade is really gone for good this time. Robin claims they can't be sure of that when the Tower's alarm systems go off, causing him to drop the conversation (and the mask) as they both head upstairs. The camera lingers on Slade's cracked mask before fading to black.
Afterward, Cinderblock is shown attacking the authorities, the cause of the alarm. He is about to throw a car at one of the officers when he is stopped by a barrage of starbolts to his chest. A fight ensues between him and the Titans, during which Robin is tossed into a nearby wooded area. Regaining consciousness, he is startled and angered to see Slade standing near a tree in the clearing. Robin chases Slade, the two of them jumping from branch to branch. Robin throws a birdarang, but misses due to a flash of light from a lightning strike. Slade taunts him and the chase through the branches resumes. Robin catches up to Slade but is unable to land a blow on him. After more taunts, Slade reveals his real plan, as Cinderblock was just a diversion: seismic generators, placed on key fault lines in the city, capable of causing an earthquake of such magnitude so as to literally split the city in two. Robin attempts to retrieve the detonator, but Slade vanishes after more lightning flashes.The other Titans find Robin in the woods and question his absence in the fight, Beast Boy explaining they had to capture Cinderblock without Robin's help, sneezing and inadvertently morphing in to an elephant. He blames the rainy conditions and claims to be getting a cold. Robin tells the group that he had encountered Slade in the woods, to Cyborg's disbelief. Questioning how such a thing is possible is interrupted by Beast Boy repeatedly sneezing and morphing. They split up to attempt to get all the generators at once, with Robin and Starfire teaming to find Slade. When the other Titans are unable to find them, despite his explicit directions, Robin begins to get foul-tempered and claims he should have done it himself. While Starfire attempts to calm him down, he suddenly sees Slade after another lightning strike and runs toward him, leaving her behind. They fight, with Robin taking many hits while being unable to land any himself, which Slade attributes to Robin getting sloppy during Slade's absence. Starfire, seeing Robin hitting the ground hard after a powerful punch, calls out to him. Slade uses this distraction to escape, running past Starfire while she's concerned with Robin. Robin yells for her to stop Slade as he rises to his feet, but she cluelessly looks around and is unable to spot Slade at all. Robin angrily grabs her arm and berates her for letting Slade get away so close to her. Confused, she tells him that there had been no one there, causing Robin's eyes to go wide with shock.
The remaining three Titans, somewhere in the city, discuss the odd goings-on: Beast Boy, having flown all around the city, has seen no sign of Slade, Cyborg's scans of the fault lines have shown no seismic generators, and he wonder's if it's not just another of Slade's tricks. Starfire, landing suddenly next to Cyborg, says she doubts Slade's involvement whatsoever. The others, questioning her meaning and Robin's whereabouts, are informed that he chose to search alone after the events that had just transpired between him and Starfire. Cyborg, determined to find out exactly what's happening, says they'll all go find Robin.
Robin is then shown to be alone in Slade's old hideout, looking for clues to this new scheme, when he spots Slade once again. Robin chases him around and is nearly crushed by a falling pile of rubble, Slade taunting him all the while. Robin asks why Starfire had been unable to see Slade. Slade explains that he had been using cloaking technology before attacking Robin. Slade explains that Robin's friends are unable to see him, unable to see the generators, and unable to stop him. Robin vows to stop him alone if need be, but is again unable to land even a single blow on Slade. Slade dodges every one of Robin's attacks, throwing him off a broken catwalk. Explaining that he'll never be able to save the city, Slade's attacks grow more and more vicious.The other Titans, tracking Robin's communicator, hear him screaming nearby. Rushing to his aid, they find a badly bruised Robin seemingly taking punches from no one. Realizing his teammates can't see Slade due to the cloaking device, he yells Slade's name in an attempt to clarify and gain their assistance. Starfire quickly charges a starbolt in her hand, illuminating the room. Robin, seeing that Slade has once again vanished, turns to the other Titans and questions them for not being out finding the generators. Cyborg explains that, being unable to find any, he thinks they're part of a ruse by Slade. Robin explains that Slade is using a cloaking device on both the generators and himself, accounting for the other Titans being unable to see either. Starfire quickly asks the obvious: if they can not see Slade, how come Robin can? Shocked, he asserts that Slade had to have been there, as he's covered in bruises and scratches and his costume is ripped. Beast Boy tells him that they're standing in front of the only exit, and that no one could have possibly gotten past them, meaning Robin had to have been alone. Robin angrily storms toward the door. When Cyborg attempts to stop him and explain that Slade is gone and there are no generators, Robin pulls out a birdarang and threatens to attack anyone who attempts to stop him. While Cyborg, Raven, and Beast Boy all stare in surprise, Robin is suddenly lit up with green energy and falls to the ground unconscious. Starfire is revealed standing behind him, her eyes glowing green, with a sorrowful look on her face that reveals she hit Robin with her starbolts to calm him down.
Waking up in the infirmary and restrained to his bed, Robin overhears the other Titans discussing his questionable state. Suddenly, Slade appears from the shadows. As Robin struggles to escape the restraints, Slade threatens him with a large electrical blade. The remaining Titans, monitoring Robin's vitals from the other room and thinking of how they can help him, notice his heart rate suddenly spike off the chart and suddenly flatline. They rush into the room in terror, only to see his bed tossed aside and the room empty. Noticing a vent in the ceiling open, Beast Boy morphs into a hummingbird to fly in and follow Robin. Suddenly, the doors and windows lock shut and Raven explains that Robin has locked down the Tower to prevent anyone from getting in or out. Beast Boy sneezes and reverts back to his normal form as Starfire attempts to break down the door. As Cyborg tries helping Starfire cut through the door, Raven reaches out with her mind to find Robin. Trying to convince Robin of Slade's non-existence, she asks him to allow her to see through his eyes so that she can see Slade as well. Looking around, she sees nothing, proclaiming to Robin that it was all in his head, when suddenly Slade attacks and Raven is sent back to her own body. She says she's unsure whether or not Slade is real, but Robin most definitely believes he is, and the stress on Robin's mind and body from the continual fighting is going to kill him.Back in the basement's warehouse, Robin and Slade continue fighting, with Slade disappearing every time a nearby light flickers. Raven, sensing Robin's forthcoming demise, alerts the others. Starfire, determined to stop it once and for all, tears a giant hole in the floor and heads for the basement. Robin, once again being beaten around by Slade without landing a blow, realizes that, despite his own bruises and cuts, Slade doesn't have a scratch on him. Robin, spurred on by one of Slade's comments, figures out that Slade is only in his mind, and only can be seen in the dark. As Slade charges toward him, he turns on the light, and Slade disappears for the last time. Starfire brings him back up to the infirmary.
Cyborg explains that Slade's mask had chemicals on it that were causing Robin to hallucinate, but they were finally all out of his system. His friends pledge that, should Slade ever return, they'll be ready and that he should get some sleep. After the girls have a laugh at Beast Boy repeatedly sneeze-morphing, Raven notices Cyborg still checking the chemical's results on the computer. He explains to the girls that the chemicals in the mask had been triggered by somebody from outside the tower, as their eyes grow wide. The light in the warehouse is shown flickering again, as the eye on Slade's mask begins to glow red which could've mean that he was still out there...
- When Raven is in Robin's mind, there is a glimpse of Robin swearing an oath to Batman. It also shows Robin's parents, John and Mary Grayson, falling to their deaths due to a trapeze wire accident during a circus performance.
- At the beginning of this episode, Silkie can be seen sleeping in the tower despite not being officially introduced until episode 36.
- The Puppet King makes a cameo in this episode.
- The glowing red eye could have been a implying to Slade working for Trigon during the time.
- Starfire's starbolt being deflected off the walls of the quarantine protocol is a reference to Star Wars Episode IV: A New Hope, when Han Solo fired a blaster bolt and it deflected off the walls of the trash compactor.
- Throughout all of Slade's fights in the episode, his footsteps as well as landing from a jump are completely silent, a subtle hint to Robin's condition.
- Robin: What are you doing here?! You're suppose to be finding the generators!
Cyborg: I don't think there are any generators, man. We looked everywhere.
Robin: Slade must be cloaking them, just like he's cloaking himself. That's why you couldn't see him.
Starfire: But if I cannot see him, why could you?
Robin: What are you trying to say?
Raven: Robin, are you sure you really saw Slade?
Robin: Saw him? I fought him! You think I did this to myself?!
Beast Boy: Dude, this is the only way out and we're standing here the whole time. No one got past us.
Cyborg: No one was in here but us.
Robin: I don't have time for this! I have to find those generators!
Cyborg: There are no generators. There is no Slade!
Robin: I know what I saw!!! I have to stop him! I'm the only one who can! (takes out Birdarang) And I'll take down anyone who gets in my way!
- Starfire: I have never seen Robin so angry before. So angry at me.
- Slade: Brings back memories, doesn't it?
Robin: All I remember is how much I hated you!
Slade: What I remember is that you couldn't defeat me... at least not alone.
- Raven: I don't know if he's real or not, but he's real to Robin, and that's all that matters. The stress on his brain is destroying his body. Robin truly believes he's fighting Slade . . . and Slade is winning.
- Slade: I am the thing that keeps you up at night. The evil that haunts every dark corner of your mind.
- Beast Boy: Ok, he's better. But what about me!?! I'm dying over here! ACHOO! (morphs into a hamster)ACHOO! (morphs into a koala) ACHOO! (morphs into a frog and croaks) Raven and Starfire: 'Laughs'