The date of Miranda's release is drawing closer, and Miranda asks Clegg if they can have a celebration. He agrees to buy nice food and alcohol and an evening dress for Miranda. Clegg is unsure whether he will ultimately keep their agreement, but he nonetheless goes along with Miranda's excitement for the night. He finds exactly the kind of dress she wants and also buys her an expensive sapphire-and-diamond necklace. Clegg even buys Miranda a wedding ring with the intention of asking her to marry him. It is not an especially expensive ring, but rather one for show: Clegg knows she will refuse him, and this will give him the excuse he needs to break his promise to free her.
He returns home and prepares the food and sets up his living space for the evening. He goes down to get Miranda at 7 p.m. She is dressed beautifully and Clegg is amazed yet frightened. For the first time, he lets Miranda walk into the upstairs regions of the house ungagged and unbound. They have a lovely evening; Miranda pretends that the room is full of people and makes Clegg laugh. She drinks sherry, seemingly unaware of her fate, not knowing that Clegg will not let her go. He gives her the necklace and they have dinner and drink champagne. They drink coffee after dinner and listen to jazz, play charades, and dance. Miranda asks Clegg what he will do after she leaves. She promises to stay in touch with him and asserts that they will become friends, but Clegg can tell that she is lying, desperate to escape. Clegg asks Miranda to marry him, but she refuses, saying she does not love him. He offers conditions: they will have separate bedrooms, nothing sexual will ever happen, she will just stay with him forever. But she does not love him, as she says once again, denying his offer.
Suddenly Clegg stands and tells her that this changes everything. He will not let her go if she does not love him. Miranda quickly reverses, saying she will marry him, but Clegg does not trust her; indeed, he has found the excuse to keep her captive that he was looking for. Miranda begs him to keep his promise. He tells her to shut up. She kicks a burning log out of the fireplace and rushes to the window and the door, trying to escape. Clegg quickly draws out his pad of chloroform and, despite his anxiety, subdues her. He puts out the fire and gets Miranda downstairs quickly. He takes off her clothes (though he leaves her underwear on), photographs her, and develops the pictures immediately.
Despite Clegg's regrets over that night - reflecting on the chloroform and the pictures, he says he is "not really that sort" - this evening marks a turning point. For several days Miranda refuses to eat or to talk to Clegg. Eventually she eats, but she is still sullen, reserved, and angry. One day she demands a bath and a walk outside. They also talk a bit, but Miranda tires of Clegg and begins to cry in anger. The next day she tries to escape once again: as Clegg is walking her back from her bath, she attacks him with a gardening axe that he had failed to put away. Yet Clegg manages to fight her back into the basement.
The next morning Miranda is apologetic and helpful. She has stopped being bitter and mean, though they are no longer as close Clegg once thought they were. She talks to Clegg, trying to figure out what he wants in order for her to be able to leave. He says it is not sex he wants, but love - and that is the one thing she cannot give him.
A few days later Miranda tries to be friendly again. She takes a bath and, afterwards, sits by the fire with Clegg. She drinks several glasses of sherry and then sits on his lap and kisses him. Clegg is confused and tries to stop her, but she persists. He is alarmed and upset by her advances, yet Miranda assures him that sexual desire and normal and that he should relax. She takes off her housecoat; she is completely nude underneath. Clegg feels sick and loses all respect for Miranda. He feels that Miranda is doing something terribly wrong. She undresses him and tries to have sex with him, but he is unable to perform. Afterward they talk, and Clegg lies about his sexuality, telling her that a doctor told him he could never have intercourse. Miranda again tries to persuade him that sex is natural, but he simply continues to be angry and withdrawn. He takes Miranda downstairs and returns to the house above, angry and embarrassed and having lost all respect for the young woman.
The next day Miranda says that she has accepted that Clegg will not release her as planned; however, as long as she is his prisoner she wants to stay in the main house, with access to daylight and fresh air. Although Clegg has no intention of fulfilling any of these wishes, he puts on a show of fixing one of the spare upstairs bedrooms for Miranda, since she threatens to stop eating if he does comply. On the day that she is to move into her new room upstairs, Miranda is excited and bossy. Clegg is full of resentment, yet is also thrilled by the possibility of playing a cruel joke on Miranda. He tells her that his condition for her going upstairs is that she allow him to take nude photographs of her. He says that these photographs would be insurance against her telling the police about him. Still resentful over her past behavior, Clegg also compares Miranda to a prostitute; upset, she screams at him to get out.
The next day Miranda is sick in bed with a chesty cough, and the day after that too. Clegg goes down to give her food several times but does not believe that she is actually sick, though Miranda is convinced that she needs a doctor. Unwilling to comply, Clegg tells her that from now on he will be giving the orders. He gags and binds Miranda, ties her to the bed and takes all her clothes off. He takes photograph after photograph of her naked, finally satisfying himself.
Miranda's sickness only worsens. She says she may have pneumonia or pleurisy and begs Clegg to get a doctor. He goes to a drugstore in town to buy her pills, but refuses to see a doctor for antibiotics because he is afraid that his scheme will be discovered. Clegg claims that Miranda only has the flu, but she insists that she is seriously ill. Over and over, Clegg keeps alluding to the fact that Miranda was sicker than she looked and that what finally happened to her was not his fault. For her part, Miranda fears that she will die and asks Clegg to stay with her. She is breathing with difficulty when, at the end of this segment of the novel, Clegg leaves her for the night.
The theme of classism surfaces prominently in this section. Clegg butts up against class distinctions when he is buying an evening dress for Miranda in town: the dress seller says she will not sell an expensive dress without a fitting first. Clegg says "If I'd spoken in a la-di-da voice and said I was Lord Muck or something, I bet...still, I've got no time for that" (79). In the end he gets the dress, but this serves to reinforce his anger at his lower-class roots (despite his new wealth) and further sharpens the divide between his world and Miranda's.
The comparison between the captive Miranda and the dead collected butterflies becomes deeper in this section, too. When Clegg sees Miranda dressed up, he says "I had the same feeling as when you watch an imago emerge, and then you have to kill it. I mean, the beauty confuses you, you don't know what you want to do any more, what you should do" (80). Disturbing for its foreshadowing, this quote shows exactly how Clegg imagines his situation: the act of killing a butterfly directly reminds him of Miranda, who is seen more and more as a prized part of his collection.
When Miranda tries to propose that she and Clegg have sex, Clegg is confused, and is convinced that his intentions have been misinterpreted: "What she never understood was that with me it was having. Having her was enough. Nothing needed doing. I just wanted to have her, and safe at last" (95). He truly does not want to have sex with her, despite what almost any other man with a female captive in a basement would presumably want to do. He only wants to observe her. His seemingly unique manner of desiring Miranda further highlights the nightmarish unreality of the situation as a whole.
Clegg's disconnect from reality has also become extremely pronounced by the end of Part 1. Miranda is horrified when Clegg goes back on his promise to free her. She is honest with him and tells him she can never love him, even though Miranda knows that such love is the only condition under which Clegg might release her. He then says that he will not free her as planned, and then Miranda herself quickly says she will in fact marry him - but Clegg refuses this inauthentic consent. Miranda is horrified by this breakdown in logic and by her own entrapment. As Clegg sums up this exchange, "The way she was looking at me really made me sick. As if I wasn't human hardly. Not a sneer. Just as if I was something out of outer space. Fascinating almost" (85). Clegg's observation about Miranda at this moment reveals to the reader (though Clegg does not see it himself) the horror and the irrationality of the situation Clegg has created. Later, Miranda will yell "God, God, it's like a lunatic asylum," after Clegg tells her to pose naked (106). The logic that motivated Miranda's imprisonment is breaking down and she can only stand by as a helpless witness.
The end of Part 1 also contains significant foreshadowing concerning Miranda's fate. When Miranda falls ill, Clegg repeats in various iterations, over and over, "It was not my fault. How was I to know she was iller than she looked" (110)? He is trying to justify actions that will apparently have disastrous consequences. Part 1 ends on a cliffhanger: the reader does not know what has become of Miranda, only that she is far more sick than Clegg knew, and that something bad will happen which Clegg thinks was not really his fault. Thus, Part 1 concludes with a tone of tension and fear. This uncertainty should keep the reader on edge all through Part 2, which will begins a week after Miranda's capture and narrates many of the events already described in Part 1, though this time from Miranda's perspective.