As Jeff fell in love with her, she convinced him of her story - she hadn't stolen the $40,000 and she had only shot Whit in self-defense. As a prelude to their torrid love affair, it didn't matter to him that he was being sucked in by her flirtatious evil nature:

Kathie (sincerely): I didn't know what I was doing. I, I didn't know anything except how much I hated him. But I didn't take anything. I didn't, Jeff. Don't you believe me?
Jeff: Baby, I don't care.

They kissed passionately, bringing their faces together, blocking the light out reflected off the tumultuous water from behind them. Jeff became a willing victim to her casual amorality.

Jeff narrates, recalling the dangerous circumstances of their meetings together. With her, there seemed to be no past or future, only the present in a trance-like state:

I never saw her in the daytime. We seemed to live by night. What was left of the day went away like a pack of cigarettes you smoked. I didn't know where she lived. I never followed her. All I ever had to go on was a place and time to see her again. I don't know what we were waiting for. Maybe we thought the world would end. Maybe we thought it was a dream and we'd wake up with a hangover in Niagara Falls. I wired Whit but I didn't tell him. 'I'm in Acapulco,' I said. 'I wish you were here.' And every night I went to meet her. How did I know she'd ever show up? I didn't. What stopped her from taking a boat to Chile or Guatemala? Nothing. How big a chump can you get to be? I was finding out. And then she'd come along like school was out, and everything else was just a stone which sailed at the sea.

They would rendezvous late at night on the beach:

Jeff: I didn't know you were so small.
Kathie: I'm taller than Napoleon.
Jeff: You're prettier too. (They kiss)
Kathie: Did you miss me?
Jeff: No more than I would miss my eyes.

They were caught in a sudden evening rainshower returning to her place, the first time she had ever invited him in: "It was a nice little joint with bamboo furniture and Mexican gimcracks. One little lamp burned. It was all right. And the rain hammering like that on the window made it good to be in there."

Blinded by love, they both were no longer able to ignore the past. Jeff decided not to inform Whit of Kathie's whereabouts and stop pretending that he would still complete his mission. He proposed that the two of them go away the next morning to "wherever it takes us...to make a life for ourselves." Both wanted to escape from the past, but couldn't deny its grip upon them. Although Jeff was confident, Kathie was fearful that they couldn't get away with it, because Whit would follow them:

Kathie: You don't know Whit. He won't forget.
Jeff: Everybody forgets.
Kathie: Not Whit.
Jeff: So we'll send him a postcard every Christmas.
Kathie: Jeff, I'm glad you're not afraid of him.
Jeff (boasting that fear hasn't prevented him from doing self-destructive things): I've been afraid of half the things I ever did.
Kathie: And this time?
Jeff: I'm only afraid you might not go.
Kathie (extending forward toward him): Don't be. I'll be there tomorrow. Love me?
Jeff: Hm, mmm.
Kathie: Poco?
Jeff: What's that?
Kathie: Little.
Jeff: Mucho.

Jeff was surprised when Whit and his loyal killer partner Stephanos arrived in Acapulco and showed up at his hotel room the next morning while he was packing. They revealed Jeff's escape from his past obligations and commitments. Whit asked Jeff casually about his progress in finding his deadly mistress. Jeff reported that he had only found her trail, cleverly lying about how she was "a clever little girl" and "always a hop, skip, and a jump ahead." To be convincing, Jeff told Whit: "I don't like playing games when I'm the fall guy. You might remember that, Whit."

Jeff led Stephanos and Whit to the downstairs hotel bar for a drink, obviously nervous that they might accidentally run into Kathie. Admitting that he blew the job when she escaped, Jeff explained his difficult commission:

Jeff: Whit my friend, there's a million dames in this world. They all look like her.
Whit: No they don't. So she was here.
Jeff: According to all available evidence, she was.
Whit: Maybe you should have sent Stephanos. Could you find one dame in a million, Joe?
Joe: And one with forty grand.

Just then, Jeff noticed Kathie enter the front door of the hotel. To divert attention, he spilled his drink across the table, causing Whit to mention his nervousness:

Jeff: Sorry.
Whit: Picked up some nerves.
Jeff: I don't need a crack like that any more than I need your dough, which is what I've been telling you. I missed her. The dame caught a boat south.
Whit: Where?
Jeff: Look, I got along before this job. I ate good and I grew as big as you did and if there's something you don't like you can say so.
Whit: I just asked where.
Jeff: Chile, Guatemala...

Outside before leaving in their car, Whit apologized to Jeff: "I'm sorry. You missed her and you feel bad. I shouldn't have joked about it." Jeff offered to return his $5,000 in expense money and turn the job over to Stephanos. Whit accepted only part of the bargain, tenaciously holding on to Jeff:

You're on. I fire people, but nobody quits me. You started this and you'll end it. Besides, Joe couldn't find a prayer in the Bible. You'll find her. Take it easy. Take your time.

Kathie and Jeff traveled to the US, taking a steamer north and moving to San Francisco, living anonymously and in secret obscurity:

It was the bottom of the barrel and I scraped it. But I didn't care. I had her.

They lived a brief period of uncertain happiness as fugitives, as they hid out to themselves in dark, secretive places:

We found a little movie house in North Beach. We were on the run. We went to places we never would have seen in our lives. And after a while, we grew a little more sure of ourselves. We drifted back to more familiar places. Ball parks and the race tracks. Why not? After all, there was one chance in a million we'd bump into our past.

At a race track after coming out into more public places, their past catches up with them. Jeff was accidentally spotted by his ex-partner Fisher, hired to track them down by Whit Sterling. Knowing if he was seen with Kathie he would be betrayed, Jeff and Kathie purposely separated, and Jeff believed he had successfully lost Fisher's tail. At a remote cabin, Kathie and Jeff were reunited: "It was meeting her somewhere like in the first times. There was still that something about her that got me - a kind of magic or whatever it was. I held her and we could laugh because we were together again. We'd played it smart and forgotten nothing. Forgotten nothing except one thing. He had followed her."

In the shadowy darkness of the cabin, Fisher proposed a deal for part of the money - if he was paid off ("ten grand and expenses, fifty/fifty, remember?"), he would keep his mouth shut and not report them back to Sterling. Fisher provoked and taunted Jeff by insulting Kathie: "Don't try to pay me off with pitch handed to you with this cheap piece of baggage." As Kathie stood by looking on, they engaged in a brutal fist-fight, their dancing shadows casting dark blotches over her enigmatic features. [The melodramatic climax to this scene is one of the strongest visual moments of the film.] Kathie panicked and shot Fisher dead. Jeff turned toward Kathie, registering on his face a shocked reaction to the shooting. This would be one of many instances in which he underestimated Kathie's murderous intent:

Jeff: You didn't have to kill him.
Kathie: Yes I did. You wouldn't have killed him. You would have beaten him up and thrown him out.
Jeff: You didn't have to do it.
Kathie: You wouldn't have killed him. He would have been against us. Gone to Whit.

As he slowly took out a cigarette and turned away from her, she raced away from the scene and left him with the body. He realized Kathie's true nature, a selfish, double-crossing betrayer. She left him to dispose of and bury the body and take the blame. He also discovered what she had left behind - her incriminating bank book with a $40,000 deposit in her account - evidence that she had lied about the money. He expressed his stunned reaction: "I wasn't sorry for him or sore at her. I wasn't anything."

After being abandoned, Jeff buried Fisher and then went into hiding in Bridgeport with a new name and profession, where he would eke out a living running a service station in a small rural town.

After arriving at Sterling's place at Lake Tahoe, Jeff assures Ann before she departs in the car back to Bridgeport that he no longer loves Kathie, although it is clear that she is on the verge of destroying him. Ann reassures him that she understands his story:

Ann: It's all past.
Jeff: Maybe it isn't.
Ann: What'll happen?
Jeff: I don't know. It's been a long time. I don't know how much he knows.
Ann: Don't go, Jeff.
Jeff: I've got to. I'm tired of running. I'd better clean this up someway. Just one thing, Ann. Do you want me to come back?
Ann: Of course.

The present action from here on contains echoes from the past - Jeff is doomed and seduced once again by the same charming, but wicked woman he had once loved and lost. Jeff becomes increasingly involved in a complex web of intrigue in a story of passion, betrayal, double and triple-crosses and death.

In his early morning meeting with Sterling, Jeff (wearing a trenchcoat here and throughout most of the remainder of the film) is greeted as if nothing had happened: "Same guy, time proof, weather proof." Whit tells Jeff: "My feelings? About ten years ago, I hid them somewhere and haven't been able to find them." Sterling requests Jeff's help "like old times" because he likes him. Jeff feels used: "You liked me because you could use me. You could use me because I was smart. I'm not smart anymore. I run a gas station."

To square their accounts and even the score, Jeff is offered one last assignment that is dangerous, but unavoidable. He is asked to retrieve some incriminating tax records from a crooked, renegade, double-dealing lawyer/accountant Leonard Eels (Ken Niles) originally from Sterling's gang. Eels has threatened to turn Whit's incriminating tax papers over to the Internal Revenue Service and charge him with tax evasion unless he is paid $200,000 as a blackmailing extortion pay-out. He finds that Kathie is living with Whit again when she casually joins them for breakfast. Obviously, Sterling knows of their past acquaintance and their double-dealing, telling Jeff that all will be forgiven if he does one more job: "You'll never be happy until you square yourself." Jeff is blackmailed by Whit and against his better judgment, reluctantly agrees to retrieve the tax records. He is blackmailed and forced to redeem himself following his previous assignment.

In the privacy of his room at Whit's place, Kathie furtively approaches Jeff to explain and profess her love for him, claiming she has returned to Whit out of fear. To Jeff, her real nature has already been revealed and he doesn't want to listen to her - he tells the lethal Kathie that he sees her for what she really is - an untrustworthy, selfish, evil woman:

Kathie: I had to come back. What else could I do?
Jeff: You can never help anything can you? You're like a leaf that the wind blows from one gutter to another. You can't help any thing you do, even murder.
Kathie: You can't say it was that.
Jeff: I can say one thing. I buried him [Fisher]. (Grabbing her) What did you tell him? About us? But you couldn't help it, could you Kathie?
Kathie: He knew it. He looked right into me. He knew it.
Jeff: How much?
Kathie: What Jeff?
Jeff: I mean about Fisher. Did he look into you for that too?
Kathie: No, I didn't tell that.
Jeff: Don't lie to me.
Kathie: I didn't. I wouldn't tell him that. I wouldn't tell anyone that. I swear it Jeff. Believe me.
Jeff: Sure, sure I believe you.
Kathie: I didn't know what to do. I was always afraid of him, and afraid of what I'd done. I couldn't live that way anymore. I couldn't stand it. Jeff, I've missed you. I've wondered about you, prayed you'd understand. Can you understand?
Jeff: You prayed, Kathie?
Kathie: Can't you even feel sorry for me?
Jeff: I'm not going to try.
Kathie: Jeff.
Jeff: Look, just get out, will you? I have to sleep in this room. Just leave it where it all is. Get out.

Jeff demands that his unfaithful lover leave his room after she has so cooly betrayed him.