Number Six is exercising in the woodlands at his makeshift gymnasium when two Guardians approach him. They ask him why he isn't using the Village gymnasium and he responds that he prefers his privacy. They accuse him of being "unmutual" and tell him that the Committee will act against him. They attack him but he easily defeats them. As they run away, they warn him that he'll have to face the committee for his actions.
Number Six is summoned to the Council Hall to come before the Committee. As he waits outside, he's informed that all those called must publicly confess using the Committee's script. One woman, Number Forty-Two, is sobbing at the thought of her crimes. Number Six watches as Number Ninety-Three is forced to go to the rostrum in the waiting room and recite the confession. He breaks into tears, saying he's not worthy, and the other Villagers applaud his repentance. Number Six goes into the Council Chamber and casually tears up his confession questionnaire. They say they're there to hear his confession: he'll be allowed no defense. When Number Six refuses, they leave for a tea break and tell him he'll undergo social and medical evaluation.
As he goes home, Number Six discovers that the Villagers are now turning their backs on him and the newspaper reports that he is being investigated. The new Number Two is at his flat when he arrives. As he snacks on crackers, Number Two warns him that no one is above investigation and there's nothing he can do if the Villagers decide to act against Number Six. He calls in Number Eight-Six and departs, and she explains that she was once unmutual but was "cured" by meeting with a social group and Number Six must meet with them as well. Number Two watches from the Green Dome and worries that they'll lose Number Six if she makes even one mistake.
The social group discusses Number Forty-Two's unmutual behaviour, with her eager participation, and Number Six amuses himself by pointing out the flaws in their arguments. They accuse him of being a rebel and walk away, and Number Six leaves only to find medical technicians ready to take him to the Hospital. One man is in a sealed chamber undergoing aversion therapy and Number Six tries to open the door without success. Another man seated nearby tells Number Six to calm down and Number Six notices a small lobotomy scar on the man's right temple. The lobo man says he was once unmutual but he was lucky enough to be cured.
The Committee summons Number Six to inform him he has been classified unmutual and one more complaint will result in "social conversion." He is under increased scrutiny with everyone instructed to report any unmutual activities he performs. Number Six can't place phone calls or order coffee at the café. The Appeals Subcommittee visit him, with Number Forty-Two a member. He refuses to yield and they leave him alone, as Number Two watches and wonders how long the loner can deal with loneliness.
Number Six walks through the woodlands, alone, and soon the Villagers all follow him at a district. Returning home, he finds the ladies of the Appeals Subcommittee waiting for him. They tell him there's only one course of action left and depart. Number Two calls to warn Number Six that there's nothing he can do and that he'll be undergoing "social conversion": isolation of the frontal lobes of the brain. The loudspeaker announcer informs everyone that they can watch Number Six's conversion operation on television for educational purposes. Going outside, Number Six finds the Villagers waiting for him. They beat him down and take him to the Hospital where he's sedated and strapped to an operating table. Number Eighty-Six explains for the television viewers that they'll use sonic waves to penetrate the skin without cutting it and destroy the centres of the frontal lobes and quell Number Six's aggressive tendencies. As the operation begins, he passes out...
... and wakes up in a hospital bed a short time later. The doctor tells him not to excite himself and says that Number Six should keep on the new bandage he has on his right temple. Number Eighty-Six escorts him out past the aversion chamber, where he sees the man from earlier being "treated." This time Number Six passively observes and does nothing. Outside, the entire Village cheers Number Six now that he has been "converted." Number Eighty-Six takes him home where Number Two is waiting to greet him. Number Two congratulates him and says they can chat later.
After he leaves, Number Eighty-Six makes Number Six a cup of tea. Dazed and confused, he still notices her slip a white pill into the drink. Acting erratically, he demands a rug and when she goes to get it, he dumps the tea in a potted plant. She leaves and Number Two comes back, speaking gently and trying to convince Number Six to tell him why he resigned. Number Six starts shouting and Number Two leaves so as to not upset him. Number Six then examines his temple and finds an actual scar. Meanwhile, Number Eighty-Six and Number Two watch him and she notes that Number Six is noticing something suspicious despite the drug he's been given that should make it impossible. Number Two acknowledges that the operation was a fake, since they couldn't risk permanently damaging the prisoner because of his value. He tells Number Eighty-Six to give Number Six an early dose of the drug and she goes to Number Six's flat. He insists on showing her how to make a proper pot of tea. He has her get the milk and sees her drug it. He smoothly switches the cups once the tea is poured.
Number Eighty-Six becomes flighty and confused and Number Two thinks she accidentally dosed herself. As she wanders away, Number Six goes through the village and meets the lobo man, asking him how he's doing. The man wonders why Number six is asking when he should be in the same condition. Number Six returns to his makeshift gymnasium and tries to regain his aggressive abilities. He doesn't have much luck but the two men from earlier come back to get revenge now that they believe he's helpless. He fights back and although initially ineffective, he rallies and defeats them both.
Number Six goes to find Number Eighty-Six, who is picking flowers in the woodlands. Number Two puts out a call for her but before she can go, Number Six convinces her to sit down with him. He then hypnotises her with his wristwatch. Aided by the drug, he has her give a report, confirming his suspicions that the entire thing was faked. He then starts to give her a post-hypnotic command to do something when the Village clock chimes at 4 p.m.
Number Six then goes to the Green Dome and, feigning dazed gentility, says that he wants to explain his resignation but thinks it would be best to set an example and do it before the entire Village. Number Two agrees and everyone is summoned to the Village Square. Number Six speaks highly of Number Two and his efforts, and prepares to confess... and the clock strikes 4 p.m. Number Eighty-Six steps forward from the crowd and accuses Number Two of being unmutual. Number Six rallies the crowd, who turn against Number Two and chase him through the streets.