In his imagination, he paranoidly fantasizes about what she might say. He first sees her in his mind in the toe-in-faucet incident in her bathtub, telling the plumber:

So he lured me down to his apartment. He made me sit on his piano bench. Then he made me play Chopsticks. Then suddenly he turned at me. His eyes bulging. He was frothing at the mouth. Just like The Creature from the Black Lagoon.

Torturing himself with his imagination, he sees the plumber (Victor Moore) telling everyone in the neighborhood about his advances. He fearfully watches the Girl in a Dazzledent commercial, openly discussing his proclivities and exposing his infidelity:

...And now that I have your attention, I want to warn all you girls and women of New York about an evil, dangerous, perfectly dreadful married man who lives downstairs in my building. His name is Sherman. Richard Sherman. S-h-e-r-m-a-n. While his lucky wife and son are in Maine for the summer, this monstrous man is terrorizing young girls in New York.

He feverishly imagines that his wife and son view the TV commercial in Maine and learn about his behavior. Believing his marriage is doomed, he phones his wife in Maine, reaching the babysitter, and discovering that Helen is on a hayride with her old beau Mr. McKenzie. Relieved, he finds that she has no knowledge of his indiscretion. As he leaves the office, he tells Miss Morris:

We've come to the end of a perfect day. Let us go home now and enjoy the simple things in life. The good things, the real things, the laughter of a child, a distant church bell, a flight of swallows winging their way back to Capistrano. Life can be beautiful, Miss Morris.

Returning home, he promises himself that he will have a quiet, unassuming and trouble-free evening, even though he is greeted from the upstairs apartment window by the Girl, blow-drying her hair. In the shower, Sherman fantasizes that Helen is accepting romantic advances on a hayride from Tom McKenzie, a writer. He frets about their possible involvement in a fling:

All that inwardly - downwardly - pulsating - and back - with - the - hair - spilled - across - the - pillow malarkey! No woman is safe around a guy who writes stuff like that - especially not on a hayride.

To retaliate, he invites the Girl to dinner and then to an air-conditioned movie on a hot summer evening. In the film's most remembered scene, the famous "skirt scene," they leave a movie theater screening. They discuss the movie they have just seen, The Creature From The Black Lagoon. She feels sympathy for the creature:

The Girl: Didn't you just love the picture? I did. But I just felt so sorry for the creature at the end.
Sherman: Sorry for the creature? What did you want? Him to marry the girl?
The Girl: He was kinda scary-looking, but he wasn't really all bad. I think he just craved a little affection - you know, a sense of being loved and needed and wanted.
Sherman: That's a very interesting point of view.

In an immortal image, finding it unbearably hot, she cools off by standing astride a vent-grating over the subways. She smiles as moving trains below blow and lift her dress upwards above her legs with a rush of air:

Oh, do you feel the breeze from the subway. Isn't it delicious?

She attempts (unsuccessfully) to keep her dress down - and it never rises above her knees to satisfy censors. Sherman stands to her side, gaping at her and commenting:

Sort of cools the ankles, doesn't it?

Soon, another train comes by, and she squeals with child-like delight as it blows her skirt up one more time. [The studio, in compliance with the Hays Code, censored her sexually suggestive line: "This one's even cooler! Must have been an express! Don't you wish you had a skirt? I feel so sorry for you in those hot pants!"]

She tells him that she is filming a Dazzledent TV commercial the next day. Trusting in him entirely, he easily tricks her into kissing him by saying that he doubts the truth of the commercials and the promise of flawless breath:

Sherman: What's that you say on the program? He'll never know because I stay kissing sweet, the new Dazzledent way. Now really.
The Girl: It's true. I'll prove it to you. (She kisses him.) Well?
Sherman: My faith in the integrity of American advertising is somewhat restored.
The Girl: You see.
Sherman: However, before I go to all the trouble of switching brands, I want to make absolutely certain. (He returns the kiss.)

When they return home, she says it was 95 degrees in her bedroom the previous night. He asks her to come into his air-conditioned apartment to cool off before she faces "a turkish bath" upstairs, and to bring her body temperature down a little. She twirls into the coolness of his living room and when he tries to engage in an intelligent conversation about psychoanalysis, she artlessly changes the subject, speaking about getting a refund for a worthless fan she had purchased and thinking of methods to keep cool.

Not suspecting any hidden motives in his actions, she decides to ask to spend the night, as he discusses Freudian theory:

Sherman: There's nothing to be ashamed of. Under this thin veneer of civilization we're all savages, man, woman, all hopelessly enmeshed. We're on a great toboggan. We can't stop it. We can't steer it. It's too late to run. The Beguine has begun. What are we going to do?
The Girl: I've been thinking about it and I, I...
Sherman: Yes...
The Girl: I'd like to stay here with you tonight.
Sherman: Mmmm...
The Girl: I'd like to sleep here.
Sherman: Are you sure?
The Girl: That is, if you don't mind?
Sherman: It's not a question of minding, my dear girl. It's just that we don't want to rush blindly into something. Look, when I said that we were savages, well, we're savages and savages...and this may be a little too savage. Now, if you want to spend an hour or so here, why...
The Girl: Please don't make me go back to that hot apartment. I haven't slept in three nights...

Then, he realizes that the fantasy he thought had come true is really an innocent request to sleep in the air-conditioning. She is very available, but strangely untouchable. He offers her his bedroom while he'll sleep on the couch in the living room: "Oh, well, that's different. Of course you can sleep here. Why not? After all, we're not savages, we're civilized people."

Sherman's paranoia about being spotted with her in the apartment is heightened when Mr. Kruhulik buzzes at the door and happens to catch a glimpse of the Girl in his living room (calling her a "living doll"), insinuating and suspecting the worst. Deciding that she can't stay the night, he sends her back to her apartment, feeling neurotic and guilt-ridden. But soon, she reappears through a trap-door passageway from upstairs, winking at him: "Hi! Forgot about the stairs. Isn't it silly. It was so easy. I just pulled out the nails. You know what? We can do this all summer!"

While preparing breakfast the next morning (making coffee and squeezing oranges), Sherman's imagination takes over - he sees the poor girl plotting and conspiring to blackmail him for money:

Plenty of ways a pretty girl could get her hands on money if she's unscrupulous enough. A girl like this could get hold of some foolish, well-to-do married man. Trap him into some kind of a situation. Bleed him till he's white. Squeeze him till he's dry. They have a word for this. They call it blackmail...(He looks for her in the bedroom, but she has disappeared.) Where is she? She's with Kruhulik. They're down at the bank, going through my safe deposit box.

He discovers her in the shower, wondering whether he should take her a big towel. He realizes he is in an awkward position: "Boy, if anybody were to walk in here right now, would they ever get the wrong idea? Cinnamon toast for two. Strange blonde in the shower. You go explain that to someone." Then, he fantasizes that Helen has returned home early, learning from Kruhulik about his dalliance. She peppers the front door with bullets, and enters brandishing a gun: "There's a woman in this apartment!" He daydreams a confrontation and a deadly shoot-out on the stairs by the scorned woman, as she shouts: "They'll give me a medal. The wives of America will give me a medal."

He admits to the Girl that he has had a bad dream, but suffers from a permanent malady - a vivid sexual imagination, due in part to a brain filled with sexual fantasies picked up from the books he issues:

Sherman: It's just my imagination. Some people have flat feet. Some people have dandruff. I have this appalling imagination...
The Girl: I think it's just elegant to have an imagination. I just have no imagination at all. I have lots of other things, but I have no imagination...Come on now, relax. You're just making this all up.
Sherman: That's right.

Lacking self-confidence, Sherman explains how his wife trusts him implicitly and takes him for granted, not even suspecting lipstick on his collar after a Christmas office party - believing it's only cranberry sauce. Doubting himself, he thinks that women only want a man who looks like Gregory Peck. She bolsters his ego and shows some kindness to reassure him, ending with her ultimate compliment and unique accolade:

Is that so?...How do you know what a pretty girl wants?...You and your imagination. You think every girl's a dope. You think a girl goes to a party, and there's some guy - a great big lunk in a fancy striped vest, strutting around like a tiger, giving you that 'I'm so handsome, you can't resist me' look, and from this, she's supposed to fall flat on her face. Well, she doesn't fall on her face. But there's another guy in the room, way over in the corner. Maybe he's kind of nervous and shy, perspiring a little. First, you look past him, but then you sort of sense, he's gentle and kind and worried, and he'll be tender with you, nice and sweet. That's what's really exciting! If I were your wife, I'd be very jealous of you. I'd be very very jealous. (She kissed him) I think you're just elegant.

When she goes into the kitchen to finish making breakfast, he answers the door, finding Tom McKenzie, who has been asked by Helen to stop by. But before he can explain why (to retrieve Ricky's paddle), Sherman's anger surfaces over his suspicions about Helen and Tom at the hayride, and over his suspicion that Helen may be seeking a divorce (because he may have a blonde 'Marilyn Monroe' in his kitchen). With an active libido and stating his devotion to Helen, Sherman knocks McKenzie out with a solid punch, after chastising him for strutting around in a fancy vest with a 'you-can't-resist-me-look."

Sherman also decides that he will personally deliver Ricky's paddle, spending two weeks on vacation in Maine with Helen and Ricky. He gives the Girl the key to his place. Before he leaves, the Girl sends him off with a big kiss goodbye: "I have a message for your wife. (A kiss.) Don't wipe it off. If she thinks that's cranberry sauce, tell her she's got cherry pits in her head." The Girl implies that a little jealousy on Helen's part will make her more aware of his sex appeal to other women.

In his haste without stopping for breakfast, he runs off to catch the early morning train, forgetting his shoes. She tosses them out the window to him and waves goodbye as he runs down the street with Ricky's paddle.