Set in the 25th century, the story centers around a man and a woman who rebel against their rigidly controlled society.

OMM: Let us be thankful we have commerce. Buy more. Buy more now. Buy. And be happy.
Female voice (medicine cabinet): If you feel you are not properly sedated, call 348-844 immediately. Failure to do so may result in prosecution for criminal drug evasion.
Male voice (jetcar radio chatter): Hey, I think I ran over some - I think I ran over a wookie back there on the expressway...
Female voice (over P.A.): Changeable. Alterable. Mutable. Variable. Versatile. Moldable. Movable. Fluctuate. Undulate. Flicker. Flutter. Pulsate. Vibrate. Alternate. Plastic.
Chrome Robot: [trying to unlock door to pursue THX] Can you hear me? Stay calm. Everything will be all right. The door seems to be jammed. Please check the lock on your side. Everything will be all right; we are here to help you. Stay calm. We are not going to harm you. Everything will be all right.
[repeated line]
Robotic Voice-Over: Are you now, or have you ever been?
Chrome Robot: You have nowhere to go. I am here to protect you.
OMM: Let us be thankful we have an occupation to fill. Work hard, increase production, prevent accidents and be happy.
SRT: How shall the new environment be programmed? It all happened so slowly that most men failed to realize that anything had happened at all.
[last lines]
Chrome Robot #1: We have to go back. This is your last chance to return with us. You have nowhere to go. You cannot survive outside the city shell. We only want to help you. This is your last chance.
Male voice (medicine cabinet): What's wrong?
Man: I need something stronger.
Male voice (medicine cabinet): Take four red capsules. In 10 minutes, take two more. Help is on the way.
[THX's case has been terminated]
Chrome Robot: We have to go back. This is your last chance to return with us. You have nowhere to go. You cannot survive outside the city shell. We only want to help you. This is your last chance.
[THX is approaching the city's exit]
Chrome Robot: Please come back. You have nothing to be afraid of.
Chrome Robot: Everything will be all right. You are in my hands. I am here to protect you. You have nowhere to go. You have nowhere to go.
Male voice: The T-H-X account is six percent over budget. The case is to be terminated.
OMM: Blessings of the state, blessings of the masses.
SEN 5241: I'll never have another roommate like OLA.
SEN 5241: Do you know you're perspiring? It's not exactly warm in here.
SEN 5241: [Meeting THX and SEN] Hello... hello. Where did you come from?
[THX and SEN don't speak]
SEN 5241: Well, it doesn't make any difference, I guess.
[SRT notices SEN's food]
SEN 5241: What's that? Food? Good, I'm starving. Do you mind?
THX 1138: What are you doing here?
SRT: I was lost.
THX 1138: ...and you're not lost now?
SRT: [Eating with his mouth full] No, I...
SEN 5241: You know the way out?
SRT: [Chewing] Um hmm...
THX 1138: Which way?
SRT: [Swallowing] That way.
[He points in the direction from which THX and SRT have just come]
SRT: .
SEN 5241: That's where we were.
SRT: Maybe you were traveling in circles. That's the way out.
THX 1138: How do you know?
SRT: [Pointing it with his hand] Look more closely.
OMM: Thou art a subject of the divine, created in the image of man, by the masses, for the masses.
[hologram plays in background while THX looks for LUH]
Hologram: Combined with economic advantages of the mating structure, it far surpasses any disadvantages in increased perversions. A final tran - An infinite translated mathematics of tolerance and charity among artificial memory devices is ultimately binary. Stimulating rhetoric...
THX 1138: LUH?
Hologram: ...absolute. The theater of noise is proof of our potential. The circulation of autotypes. The golden talisman underfoot is phenomenon approaching. And, in the history of now, all ethos are designed.
Male voice: Remember, thifty thinkers are always underbudget.
SEN 5241: I want you for my roommate.
[THX leaves]
SEN 5241: We'll be happy!
Male voice (P.A. in garage): ...critical noise levels in this area. Be sure to report all decibel surges in excess of 1.5 on the Murrer-Wiggins scale.
Male voice: Economics make it necessary to terminate any operation which exceeds five percent of its primary budget.
THX 1138: I think I'm dying.
OMM: Can you be more specific?
Female voice: Performance perfect is perfect performance.
SEN 5241: [prison] I want an idea that is clear, simple and plain as the nose on your face!
[another prisoner punches him in the nose]
SEN 5241: You know, when I was at school, it was all very different. We used to stay in bed all the time. Combined primary economics... Combined primary economics was a bottle about this big.
[holds hands two feet apart]
SEN 5241: Took a week.
Child: Wow!
SEN 5241: [kneeling in a studio before a large image of OMM] Things don't seem to make sense. Sometimes I see things get left out, and... they don't fit. People don't seem to see them. Or they don't know what to do. Sometimes I - Sometimes a little - a little adjustment -
[laughs]
SEN 5241:
Monk: This is no place for prayer. If you want to speak to OMM, you must go to a unichapel. You know that.
SEN 5241: Yes.
Monk: What? Are you in any trouble?
SEN 5241: No, I - I'm okay, I'm going now.
Monk: What's your number and what's your prefix? I'm going to see this gets into your report.
SEN 5241: [stammering] No, I'm leaving now.
Monk: I'm sorry, I - I have to report all intruders. Uh, where's your identification badge?
SEN 5241: I... lost it.
Monk: You're in violation. I'm gonna have to report you to the authorities.
Male voice (P.A. in hallway leading to garage]: ...in your zoned section for longer than three minutes. Jet acceleration will not be safe to persons in dispersal area. To avoid being singed by jet exhaust, please exit your vehicle on the right, and walk through the blue zone on the left.
Male voice: T-H-X eleven-thirty-eight will be taken into custody at a minimal monetary expenditure. Total operation cost: six thousand credits under budget. Congratulations. Be efficient, be happy.
THX 1138: I don't understand, what happened to LUH, she was here.
[in crowded hallway]
Male voice (P.A. in hallway): Keep causeways clean. Save time, save lives.
Male voice: That accident over in Red Sector L destroyed another 63 personnel, giving them a total of 242 lost to our 195. Keep up the good work and prevent accidents. This shift is concluded.
[first lines]
Male voice (medicine cabinet): What's wrong?
THX 1138: Nothing. Nothing really. I just feel that I need something stronger.
Male voice (medicine cabinet): If you have a problem, don't hesitate to ask for assistance.
THX 1138: Yes, thank you, I'll be alright.
Male voice (medicine cabinet): Call 3485...
LUH: I'm going to have a child. Poor me!
SRT: I don't know. All that stuff, cybernetics, genetics, I don't understand it. I guess holograms aren't meant to.
SRT: [THX is looking at a screen that says LUH has been "consumed" and her name has been reassigned to a bottled fetus] Well, either this thing has gone nuts, or that's your roommate.
THX 1138: Who are you?
SRT: I am a hologram.
Female voice: What's wrong?
Man on monitor: I just bought one of these yesterday, and it doesn't fit my consumer, and the store doesn't have any of the other kind.
[LUH presses a button]
Male voice: For more enjoyment and greater efficiency, consumption is being standardized. We are sorry...
Man on monitor: This is -
[cut off]
LUH: I was so afraid. So alone.
SEN 5241: You know I've always had a way with computers.
Trial Prosecutor: Economics must not dictate situations which are obviously religious.
SEN 5241: Our differences are differences of emphasis.
Female voice: A libido leveler has been mislaid near the pulse-leveling gate. If you have accidentally...
SRT: Well, maybe you are right. Maybe there's something wrong with the computer. I don't know, it's a strange life. Cybernetics, genetics, lasers and all those things. I guess I'll never understand any of that stuff. Guess maybe holograms are not supposed to.
Hologram Newscaster: ...units of detuned escalatories have not, however, prevented virus and ordnance from invading our centers.
SEN 5241: [a prisoner jumps repeatedly on a downed robot] Now that's what I call the wrong idea.
THX 1138: [In a confession booth] Who am I to her, she to me? Nothing! Just an ordinary roommate. We share nothing but space.