The Titans were reunited by Raven, who had been seeking help against her demon-father, Trigon. The Titans exiled Trigon into another dimension in the early issues, but, as things continued, Raven had to struggle to keep her Power Incontinence at bay. One day, all hell broke loose — and we mean it!
One day, after a mishap in training, Raven announces she will leave the team the following night. The Titans are worried, but don't know how to help her. Jericho tries an alternative approach: possessing Raven's body while she's sleeping. He is transported to Trigon's dimension, where Trigon is ready to give him A Fate Worse Than Death. Then Raven appears and somehow, shaken but alive, Jericho returns to Titans Tower. However, Raven is nowhere to be found, and all the skies on Earth have turned dark.
Lilith turns up, wanting to help the Titans. They try to summon Raven's soul, with the help of former Kid Flash, Wally West, who had previously left the team as his super-speed was killing him. The summoning fails, and the Titans are instead pulled to Azarath, Raven's home dimension, which has just been destroyed by Trigon. In the meantime, Trigon himself shows up on Earth, along with Raven, who has been corrupted by her father's power.
By the time the Titans return to Earth, Trigon has taken it over and corrupted it. Raven sends the Titans into an illusion, where they fight against evil versions of themselves. As each Titan is pushed to the edge and kills their dark halves, they are corrupted themselves. But Lilith takes control of the evil Titans, using them to kill Raven. When it is done, the Titans are cleansed and return to normal, and try a last-ditch attack against Trigon. Azar manifests through Lilith and instructs Arella on what she has to do with Raven's corpse. They release her soul-self, now cleansed of Trigon's evil and reinforced by the souls of the dead Azarathians. Raven's white soul-self slays Trigon, Raven herself reappears for a moment and disappears, and everything is soon back to normal...except nothing is. Raven is now dead, Trigon is no more, and Titans Tower has been obliterated.
The Terror of Trigon contains examples of:
- All According to Plan: Two cases in a row.
- First, the evil Raven was expecting the Titans to kill their evil selves: by doing so, they became evil themselves, corrupted by Trigon's power.
- But Lilith was counting with it as well: she (under Demonic Possession) was controlling the Titans, and when they were corrupted with Trigon's power they got the power needed to kill Raven.
- And I Must Scream: Jericho experienced several of those. But, being mute, he can't scream, ever.
- Attack! Attack! Attack!: The world is dead. There is nobody else but the Titans. There is nothing around but a corrupted wasteland. No cavalry will come to their rescue. Nightwing is a master tactician, but here, there's no strategy possible, rather than just hit Trigon with everything they got.
- Battle in the Center of the Mind: Once Trigon arrives, literally the entire world population is trapped in torturously posed, warped stone statues, superheroes, aliens, and all, in which it is heavily implied that Trigon is torturing them with his signature red-eyed monochrome doppelgangers.
- Because Destiny Says So: Lilith left the Titans on bad terms the last time, but she showed up to help anyway. She felt that her powers would be needed.
- Chekhov's Gun: Raven's rings, gifted by Azar, turn out to be much more powerful than originally thought.
- Continuity Nod: Crisis on Infinite Earths, published a short time later, included all the important, semi-important and unimportant characters of DC Comics, but Raven was conspicuously absent. Have you ever wondered why? This story is why.
- Defying the Censors: The Comics Code did not approve the on-panel scene of Dick and Kory sharing a bed, but losing the approval meant Marv Wolfman and George Perez could get away with a lot more horror elements than they normally would.
- Demonic Possession: The evil doppelgangers gain control of the originals after each Battle in the Center of the Mind. The evil version of Raven is actually a result of Raven's soul-self being removed and her body filled up with Trigon's power instead.
- Diabolus ex Machina: Because Trigon's doppelgangers torment the Titans with their inner demons, it will be easy to get confused by the sight of the Titans apparently overcoming those inner demons and killing the doppelgangers as a sign of their personal victory over their personal problems. Hahaha, no, all that means is that the doppelgangers actually get to control their original bodies now.
- Heads I Win, Tails You Lose: Trigon's statues and evil doppelgangers: if you remain in statue form, the doppelgangers torment you forever and Trigon feeds on your negative emotions; if the doppelgangers succeed in driving you into a murderous frenzy and you kill them... you're no longer in statue form but the doppelgangers take you under Demonic Possession instead.
- Light Is Good: The white soul of Raven, cleansed from Trigon's corruption, and reinforced by the souls of Azarath. A force of pure good attacking and destroying Trigon, who is pure evil. Then Raven emerges from the light, completely purified, and disappeared.
- Light Is Not Good: Azarath, after being destroyed, was just an empty void of white light.
- Mordor: And much more disturbing, because some hours before, it was New York.
- Planet Eater: Trigon wants to consume all the souls of all the living creatures of the universe, to recreate his own one (which he had just destroyed).
- Red Eyes, Take Warning: When the Titans killed their dark versions, they got red eyes, before becoming evil themselves.
- "The Reason You Suck" Speech: Each evil Titan gave one to their respective hero, inside their illusions:
- Nightwing appeared in a lab, and the evil Nightwing pointed him that Batman has just died. And because of him, because he left him, and let him go around with that useless brat Jason Todd. Just look at him, Batman has died, and he can't do anything but cry! Do you want to undo this? Take back the Robin suit! Go back to be twelve years old! Be a sidekick again!
- Starfire saw Tamaran in ruins, as the Citadel has decimated it and took the Tamaraneans as slaves, including her father, mother and brother. All because of her, because she left Tamaran and had fun and romance on Earth while her people suffered! Do you want to undo this? Wear those chains! Be a slave once more!
- Wonder Girl saw her evil self kill Terry Long, breaking his neck. What a shame, such a powerful Amazon, getting married with such a weak man. Do you want to undo this? Ignore your past! Forget the insignificant weak human race! Forget the Amazons, you are not a true Amazon after all! Become an all-powerful bitch!
- Cyborg saw Sarah Simms completely terrified by him, and the kids openly insulting him. He's insulted by Víctor Stone, his evil self who is completely human. Look at you, you are a robotic monster! You don't have the right to walk among normal people! You don't have the right to expect to have a girlfriend! Do you want to undo this? Take out all your robotic implants, and let's see how much of a man is left!
- Changeling saw his evil self killing his fathers, the Doom Patrol, Terra, and everybody else that Logan has ever loved and died. All those deaths were caused by you, so enjoy your bodycount! Here, take a piece of Robotman, he tastes delicious! And let's see who comes next! Dayton? Questor? Jillian? The Titans?
- Wally West saw the evil Kid Flash having sex with Raven. Yes, you two had a lot of Unresolved Sexual Tension, but she will never be yours! You are not enough of a man to enjoy her warm kisses! You are sick, and you never said it to the Titans, because they would laugh at you! Do you want to undo this? No, you don't, you are an undecided wuss. So say goodbye to Raven, as evil Kid Flash takes her away at super speed!
- Sadistic Choice: For all the human race. If you betray Trigon (and "betray" can include even "don't understand what's going on"), prepare for a horrible and gruesome death. If you accept Trigon's rule, without hesitation or doubt, be prepared for what Trigon has in store for you: a horrible and gruesome death.
- Suspiciously Similar Substitute: No sooner has team mystic Raven done her Face–Heel Turn than the team's previous mystic, Lilith, shows up to help. This is lampshaded in the Breather Episode that follows the arc, where Lilith says that as long as she's with the Titans, she'll only be seen as "Raven's replacement."
- Took a Level in Badass: Trigon, from Doomsday's level of power to Galactus' level of power.
- We Are Experiencing Technical Difficulties: The inevitable result when the reporters thought that filming the speech of Trigon would be an exclusive coverage.