Back at Beth's apartment in her living room, Nick immediately forces himself on Beth, pinning her arms up on the wall, kissing her forcefully, and ripping her dress open in the front. In the misogynistic, near-rape scene, he lustfully pushes his hands under her bra, scoops out her breasts, and kisses her even harder. Then he aggressively drapes her over the sofa as she protests: "Nick, stop, no!" He pulls off his own pants and animalistically enters her from behind, climaxing quickly.

Slightly later, they are lying together on their sides - her torn dress is wound around her as they casually talk about Catherine Tramell:

Nick: You had her pegged. She used her book as an alibi.
Beth: I met her at Berkeley. (He takes notice and sits up) We were in some of the same classes.

Beth is very upset at his crude, impersonal love-making - and soon after, curtly directs him to find his way out of her apartment:

Beth: You've never been like that before. Why?
Nick: You're the shrink.
Beth: You weren't making love to me.
Nick: Who was I making love to?
Beth: You weren't making love.

The next morning in the bureau office, the detectives have made phone calls over to Berkeley and have established that "there was a murder in '80. A professor, in his bed, multiple stab wounds with an icepick." And university records confirm that Catherine Tramell was a student there at the time. Walker orders his group to "move on it," and then instructs Nick to tail her: "You see where she leads."

That day, Catherine leaves her Stinson house, driving her black sportscar into Marin County along the winding, twisting two-lane highway. Nick follows a safe distance back in an unmarked police car as she dangerously cuts in and out while passing cars at a very fast speed - the tense scene is sharply edited and shot mostly from Nick's point of view as he tries to keep up with her. At one point, he slams on the brakes and sounds his horn around a blind curve, skidding back into his own lane and just barely missing a large Gray Line Tours Bus. Frazzled, he loses her, but then locates her black car parked in front of a Mill Valley house.

Nick parks a short distance away and walks over to the small, plain house. He reaches into the mailbox and takes out an envelope addressed to HAZEL DOBKINS, 26 ALBION ROAD, MILL VALLEY, CA 94941. By twilight, Catherine comes out of the house with an older-aged woman - Hazel Dobkins (Dorothy Malone). He continues to follow her car from a distance through an intersection when she suddenly engages him in a thrilling car chase. She guns her engine through a stoplight turning red. He is blocked by two other cars in front of him and is unable to pursue her any further. He drives to her Stinson Beach house, where he locates her car already parked in the driveway.

He enters the gate into her outdoor, heated swimming pool area - steam rises from the water. In the red light of an upstairs bedroom where the curtain is drawn open, Nick watches Catherine remove all of her clothes and caress herself gently with a scarf. The light goes out and the room turns pitch black.

Nick investigates Catherine and her acquaintances on his office computer - its screen fills the frame - he types in information about Hazel Dobkins. The computer returns the line: "NOTHING CURRENT, 1991." He adjusts the year back to 1965, and the computer replies: "RELEASED, SAN QUENTIN, JULY 7, 1965." Her "prior arrest record" reveals: "HOMICIDE, JANUARY 10, 1956, SAN FRANCISCO." Gus appears behind him to report his findings from his investigation at Berkeley: "One dead psychology professor, Noah Goldstein. Dr. Noah Goldstein. And guess what? He was her counselor." And Catherine wasn't even a suspect: "Never even got a statement from her." And Gus is already aware of the notorious homicide case involving Dobkins who was imprisoned for nine years for the crime: "Nice little housewife, three little kids, nice husband, wasn't porkin' around, no financial problems. One day, outta the clear blue sky, she does 'em. All of 'em. Used a knife she got for a wedding present. Didn't even deny it. Sweet as honey. Said she didn't know why she done it."

Suspicious but also intrigued by her dangerous personality, Nick visits Catherine's home again and is invited to go upstairs, but he pauses at her work table when he notices newspaper clippings about him spread around: "KILLER COP TO FACE POLICE REVIEW," "Tourists Killed by Cop," "Cop Cleared in Tourist Shooting," and "Grand Jury Probe Continues." With beguiling provocation, she turns and explains how he has become her next 'fictional' protagonist:

I'm using you for my detective in my book. You don't mind, do ya?

At the upstairs bar, she uses an icepick to chip at the ice for their drinks, admitting that she prefers crushed ice over ice cubes - "I like rough edges." Then, she asks him about the tourist shooting: "How does it feel to kill someone?" As Nick explains the accident, he is uncontrollably seduced and mesmerized by her evil, powerful charm, not realizing how deeply she has researched his background and knows his proclivity toward violence in the line of duty. Catherine's line of work also requires her to be associated with killers, and she teases him with her sexuality to learn about his violent past - [the scene resembles Hitchcock's Notorious (1946) with its prolonged conversational scene mixed with kissing]:

Nick: It was an accident. They got in the line of fire.
Catherine: Four shootings in five years. All accidents?
Nick: They were drug buys. I was working under cover. You want to tell me about Professor Goldstein?
Catherine: Ha, well, there's a name from the past.
Nick: You want a name from the present. How about Hazel Dobkins?
Catherine: Noah Goldstein was my counselor in my freshman year. That's probably where I got the idea for the ice pick - for my book. Funny how the subconscious works.
Nick: Hilarious.
Catherine: Hazel is my friend.
Nick: Well, your friend took out her whole family.
Catherine: Yes. She helped me understand homicidal impulse.
Nick: I thought you had learned that in school.
Catherine: Only in theory. But you know all about homicidal impulse, don't you Shooter? Not in theory - in practice. What happened? Did you get sucked into it? Did you like it too much?
Nick: I don't know what you're talkin' about.
Catherine: Tell me about the coke, Nick. The day you shot those two tourists - how much coke did you do? Huh? Come on, you can tell me. (She steps closer and approaches his lips for a face-to-face kiss)
Nick: I didn't.
Catherine: (teasing) Yes, you did. They never tested you, did they? Internal Affairs knew. Your wife knew too, didn't she? (He grabs her hand roughly and pushes it away) (whispering) She knew what was goin' on. Nicky got too close to the flame. (He grabs her hand again and twists it behind her back) Nicky liked it. (Their bodies and faces are pressed closely together) That's why she killed herself. (He pushes her back, looking at her with a mask-like expression on his face)

Their conversation ends abruptly when Roxy, wearing a black T-shirt, black leather jeans and black boots comes into the room. Catherine greets Roxy ("Hi hon"), her lesbian girlfriend. She flaunts her bisexuality in front of him by kissing Roxy, fondling her nipple, and then standing with her arm around her and asking: "You two have met, haven't you?" As Nick strides out, obviously threatened by Catherine's sexual bond with the snarling woman, she promises: "You're going to make a terrific character, Nick."

Without being properly announced and admitted, Nick storms into Beth Garner's office in police headquarters and demands to know: "Who has access to my god-damn file?" Although "it's a confidential psychiatric record" and illegal to distribute, he backs her into a door for a confession - making her blurt out "Nilsen." Internal police enmities are now out in the open. He charges directly into the Internal Affair's office and into Nilsen's private office, slams Nilsen against some file cabinets, and accuses him of selling his I.A. file to Catherine Tramell. How else would she know so much about him? At gunpoint, other I.A. officers make him back off. Nilsen shouts after the corruptible cop: "You f--ked yourself, Shooter. You hear me. You are out! You are out!" As Nick drives away from work, he reveals to Gus how paranoid and fearful he has become: "She knows where I live and breathe. She's coming after me, Gus."

That night at Nick's apartment, Beth knocks on the door and then lets herself in with her own key, but Nick refuses to speak to her. She yells back: "Dammit, don't shut me out. You owe me more than that." He removes her key from her key ring, and cruelly discounts their on-again/off-again relationship:

We went to bed, what - ten, fifteen times maybe? It wasn't memorable enough to carry an obligation.

Then, he sarcastically suggests a way for her to combat her hostility toward him through a different sexual relationship: "Why don't you get yourself some friendly little therapist and work out some of that hostility? And maybe you can get off once in a while." Furious and hurt, she hurls herself at him, but he blocks her arm - and then lets her go. She explains why she let Nilsen have his confidential file: "He was going to recommend your discharge from the force. He didn't buy my evaluation. He said I wasn't objective. So I made a deal with him to review the session notes himself. I didn't think he'd show them to anybody."

With the TV blaring a B-grade horror film later that night, a hung-over Nick is awakened by the ringing of his phone. After receiving what appears to be a disturbing phone call, he drives to the scene of a crime - Lt. Nilsen is slumped over the steering wheel of a black car in an alley - he has been shot at close range in the head by a .38 caliber revolver. Lt. Walker asks for Nick's gun - he is considered a suspect in the killing after his temper tantrum in Nilsen's office.

Nick is interrogated in the same room where Catherine sat. Weak in his own defense, he glumly admits that he has no evidence that Nilsen showed his psychiatric file to anyone. To his surprise, Beth defends him: "I saw Detective Curran at his apartment about ten o'clock last night. He was sober and lucid. I asked him in my capacity as his departmental therapist about his altercation with Lt. Nilsen. He expressed regret and displayed no hostility." Copying Catherine's defense, Nick illustrates the absurdity of his situation:

Nick: I'm gonna storm into his office in front of everybody in the middle of the day and kill him that night? I'm not that dumb.
I.A. Investigator: Going after him before gets you off the hook for killing him: that's your alibi.
Lt. Walker: Like writing a book about killing a guy gets you off the hook for killing him.
Nick (in an ironic tone): Good point.

Pending the outcome of a psychiatric evaluation, Curran is ordered to go on leave. He catches up to Beth and sincerely thanks her for helping his case:

Beth: How do you know Catherine Tramell saw your file?
Nick: She knows things about me that I only told you.
Beth: She must really be something - (smiling) - from a clinical point of view.
Nick: What was she like in school?
Beth: I hardly knew her. She gave me the creeps, though. I don't know why.

He apologizes for his mean words to her:

Nick: Beth. I didn't mean what I said yesterday about...
Beth: Yes you did. I'm a big girl. I can handle it.

The next day as Nick packs up his things at the police headquarters, he is inquisitive about the accident which took the lives of Catherine's parents. The results point to Catherine's guilt once again:

The boat blew. There was a leak in the fuel line. There'd been two previous repairs. They had a five-mil policy on both of 'em. A real heavy investigation but they got zilch. A big goose-egg. It was an accident.

Walker recommends that Nick "stay in touch with Dr. Garner - it'll help on the evaluation." [The juxtaposition of their line hints at deeper conflicts and other options in the plot-line]:

Nick: She killed him, Phil.
Walker: Beth? Now you've got Beth killing people?
Nick: Catherine Tramell. It's part of her game.
Walker: First you've got her stealing your file. Now you've got her killing Nilsen? Forget about her, for Christ's sake. Go somewhere, sit in the sun, get her the hell out of your system.
Nick: You don't buy it, do you? She knew nobody'd buy it. She knew I'd say she did it. And she knew that nobody would buy it.
Walker: She is screwing with your head, Nick. Stay away from her.

Nick finds Catherine's black car outside his place and she is sitting on the front stoop waiting for him, making a suggestive comment about his nickname: "I heard about what happened. What good's a 'Shooter' without his gun?" She explains her sources of information came through her wealthy connections:

Catherine: I have attorneys. They have friends. I have friends. Money buys a lot of attorneys and friends.
Nick: I wouldn't know about that. I don't have any money. I don't have any attorneys. And Gus is my only real friend.

As he prepares drinks for them, he takes out a huge hunk of ice, and begins breaking the chunk with a $1.65 K-Mart ice-pick: "I was expecting you." She takes an experienced turn with the pick: "You like watching me do it, don't you?" He lights a cigarette for her and places it between her parted lips. Preferring not to be called 'Shooter' any more, Catherine asks: "How about if I call you Nicky?" - the name his wife used to call him. They toy with each other, not really knowing where they are "going" with it:

Catherine: Do you have any coke? I just love coke with Jack Daniels.
Nick: I've got a Pepsi in the fridge.
Catherine: It's not really the same thing, now is it?

With her seductive, challenging style of confrontation (mind games which precede eventual sex games), she presents him with one of her paperback books - The First Time - a story "about a boy who kills his parents. They have a plane. He makes it look like an accident...To see if he could get away with it." As she leaves his place, she proposes that he follow her after midnight to Johnny's club. Gus advises his pal to stay away from her: "Everybody she plays with dies."

Later that night in Johnny Boz's decadent club (constructed from a church) which is pulsating with the ear-splitting beat of dance music, Nick catches a glimpse of Roxy dancing with another woman. He follows her through a sea of bodies into the MEN's room, where both men and women are popping pills and smoking crack. She walks into a toilet stall where Catherine is seated and sniffing a powdery substance with a black man. Roxy straddles her on the toilet just as Catherine looks up and sees Nick watching. To hide his view, she closes the toilet stall door with her foot.

Wearing a completely back-less dress, Catherine first dances with Roxy and the black man, as Nick watches her sensual body movements and the way she kisses Roxy. With a beguiling look, Catherine turns with her back toward Roxy, permitting her female lover to touch her breasts. In an instant, Catherine leaves Roxy, presumably to provoke and enflame the jealousy of her female lover. Catherine's live-in lover must resort to dancing with a black man. Catherine becomes his dance partner - he rubs her butt against his crotch. He turns her, suddenly grabs her ass, presses her toward himself, and then starts kissing her on her neck and lips. Feverishly, they consume each other in the middle of the writhing, turning bodies of other dancers.

The scene immediately transitions to the infamous, intimate, graphic, roughhouse sex scene between Nick and Catherine in her mansion in San Francisco. Her face, in full frame, is gently reclining on a bed beneath his. Atop her, he removes both his pants and shirt and then extends his entire naked body down onto her. First, he kisses and cups his hand around one of her breasts and then moves down her body. He doesn't know whether he is being set up for the next killing and will be the next to die. In the same bed where Johnny Boz was murdered, he enthusiastically performs oral sex on her - she arches her back with pleasure. They switch positions - she is atop him, kissing him and reciprocating with full body kisses. Reminiscent of the opening scene of the film, Nick looks up during their love-making and sees their reflection in the ceiling mirror. Their sex grows rougher as he turns her over and their bodies are pressed together - she moves her legs apart. As their sexual tension mounts, their groaning increases and she grabs the brass frame of the bed behind her, and then digs her nails into his back - blood oozes from the deep scratch marks.

She turns him over again and kneels over him, quiets him down, and holds his arms above his head. She reaches under a pillow next to his head for a white silk scarf. He sees it - considers what it may mean - and they both challenge each other with their eyes. Excited by bondage, she binds each of his hands to the brass bed frame behind his head and then thrusts her hips into him. Her head and back arch outwards, her breasts reach high, and they continue grinding into each other as she strains and extends her arms back - at the moment of climax, she falls into him and pounds her fists down next to either side of his head. There is a violent edge to their climaxing - Nick is both frightened and excited by her. He might deliriously expect an ice-pick to be thrust into his chest, but his pain/pleasure fantasy isn't fulfilled. She gently unties him and they embrace each other.

Later, she is asleep next to him, naked, and he smokes a post-coital cigarette. He gets up and strolls butt-naked into the bathroom. There, he runs the faucet, cupping his hand to drink and to douse his face. As he comes back up from the sink, there is leather-clad Roxy fully-dressed in the mirror behind him - he is startled to encounter her. She is expressionless, but insanely jealous. Speaking to her "man to man," he boldly brags about his recent sexual conquest:

Roxy: If you don't leave her alone, I'll kill you.
Nick: Let me ask you something, Rocki. Man-to-man. I think she's the f--k of the century. (Long pause) What do you think? (She looks like she might spring and attack) How long have you been here? You like watching, don't you? 
Roxy: She likes me to watch. (She turns and leaves)

His weak bravado and fragile nakedness surface when her retort reveals that she, a lesbian lover, is encouraged to watch Catherine's heterosexual couplings with men.

Nick returns to the bedroom and slips into bed next to Catherine. She kisses his hand and murmurs softly: "Nicky". In the morning, sunshine floods the room as he jerks awake, but she is not there. She has left a note on her side of the bed: "the beach C." He hurriedly drives to the Stinson beach house, walks around the house, and finds her on the rocky path behind the house next to Roxy. Roxy gives him a cold look as he passes, and he follows Catherine to the edge of the rocky bluffs, where a bonfire is burning in a open stone fireplace. She is wrapped in a white blanket.

He kisses her - framed behind the flames - and they begin talking about their violence-tinged night of love-making. He is totally intrigued by her and engaged in a dangerous game, underestimating her calculated amorality and destructiveness. Her exciting, clever mind games, coupled with physical sex, release the pressures that have built up inside of him - a release valve that he couldn't open in sex with Beth:

Nick: I guess, uh, Roxy's not takin' this too well, huh?
Catherine: She's seen me f--k plenty of guys.
Nick: (offers a teasing boast) Maybe she saw something she's never seen before.
Catherine: She's seen everything before.
Nick: Honey, I'd thought I'd seen everything before.
Catherine: Did you really think it was so special?
Nick: I told her I thought it was 'the f--k of the century.' (She gives a slight laugh and turns to walk toward the steps leading down to the beach) Well, what do you think?
Catherine: I thought it was a pretty good beginning.
Nick: What about Roxy? Is she more fun?
Catherine: Would you like her to join us sometime?
Nick: Did she join you and Johnny?
Catherine: No, Johnny felt intimidated.
Nick: And look what happened to him.
Catherine: Tell me, Nicky. Were you frightened last night?
Nick: That's the point, wasn't it? That's what made it so good.
Catherine: (She stops) You shouldn't play this game.
Nick: Why not? I like it.
Catherine: You're in over your head.
Nick: Maybe - but this is how I'll catch my killer.
Catherine: (She smiles and starts walking down the beach again) I'm not gonna confess all my secrets, Nick, just because I have an orgasm. You won't learn anything I don't want you to know.
Nick: Yes I will - then I'll nail ya.
Catherine: No, you'll just fall in love with me.
Nick: I'm in love with you already. (He kisses her) But I'll nail ya anyway. You can put that in your book.

Already in love with Catherine after one night of violent passion, Nick meets up with Gus in a country-western bar. Gus is drunk and staggering - and finally sobers up in a diner, angered and concerned about his partner having sex with a possible murder suspect and the jeopardy he is putting himself in. The investigation has found that Nilsen was paid a large sum of money as a bribe - possibly by Catherine - to view Nick's file:

Gus: You wanna die, Hos? What is it - those goddamn tourists? You still feel so bad about that you're wigglin' your way into an icepick?...
Nick: I'm not afraid of her.
Gus: (loudly) Why the hell not?
Nick: I don't know. I'm just not.
Gus: That's her p---y talking. It ain't your brain. I.A. done did a track on Lt. Martin D for Dickhead Nilsen. They found a safety deposit box with fifty-thousand dollars in it, taken out three months ago, and not used since.
Nick: It doesn't make any sense. She didn't know me three months ago. 
Gus: Maybe it wasn't her that paid him. Maybe the money was for somethin' else. How the f--k do I know? I'm just an old city cowboy tryin' not to fall outta his saddle.

Outside the diner after he parts from Gus, Nick is followed by a black car (with its lights off) as he walks down the street. Suddenly, the car speeds up, its lights go on, and it bores down on him as its target - he hurls himself above the car to avoid being struck. He bounces off the hood and lands hard on the ground behind it. The car slams on its brakes, goes into reverse, and burns rubber straight back at him. He narrowly avoids being hit a second time. He jumps into his own car to pursue the black car as it speeds away. The scene is a combination of stunt driving, screeching tires, wild turns, and cars bucking up stairs and sailing headlong through the air down North Beach's steep streets. The black car finds itself in a dead-ended construction area and there is no way out except back toward Nick's car. He plays chicken with the black car, driving head-on for it. At the last moment, the black car swerves out of his way, goes out of control, and makes a spectacular crash landing - it lands upside down. Nick turns over the driver - the blonde has her eyes open but has died with a broken neck - it's Roxy.

As Lt. Walker and other I.A. investigators and police extract the body and tow away the black car, Nick makes a statement, describing the incident as "an accident," and then reveals that he "knew her" - Roxanne Hardy, last known address, Cloverdale, California. No priors, no convictions. Her car is registered to Catherine Tramell. The I.A. agent, thinking Nick is "out of control," orders him to appear in Dr. Garner's office at nine o'clock the next morning. He sarcastically replies: "Who are you guys gonna sell my file to now, huh?"