Out of the Past begins when Joe Stefanos drives into Bridgeport, California as he looks for private detective Jeff Markham. The owner of the small town’s gas station, Jeff Bailey, is secretly Markham who’s hiding out from Stefanos and his boss, Whit Sterling.
However, Jeff isn’t there. He’s out fishing with the local hottie, Ann Miller, but Joe gives Jeff’s deaf and dumb employee, The Kid, a message to give him. Ann’s parents distrust Jeff, and Ann’s childhood beau, Jim, completely detests him because she reciprocates Jeff’s affections.
Jeff is wary of Joe’s arrival in town, but he agrees to drive to Lake Tahoe to meet Whit as he knows he can’t run forever. He asks Ann to ride with him so that he can tell her the truth about his past.
In true noir style, there’s a flashback where Jeff reveals his real last name is Markham, and that he was once a private investigator in New York City with a partner named Jack Fisher. Whit Sterling hired him to find his girlfriend, Kathie Moffatt, after she tried to kill Whit, and then ran off with $40,000 of his money.
Knowing that bringing Kathie back to Whit will result in her death, Jeff balks at the job. However, Whit gives Jeff his word that he won’t harm her, and states that he only wants her back. Jeff takes the job in which Whit will pay him $5,000 now and another $5,000 when he finds Kathie plus all expenses for his troubles. Jeff’s partner demands half the money even though he’s not part of the job since the two are partners, and they are supposed to split everything 50/50. Jeff has no problem with that request, and he heads off to track Kathie down.
Jeff finds Kathie’s maid, and learns that she left for Florida, but based on the shot’s her doctor gave her before she skipped town, Jeff decides Mexico is a more likely destination. He winds up in Acapulco where he does find Kathie.
You can never help anything, can you? You’re like a leaf that the wind blows from one gutter to another.Jeff Markham
The two become friendly over the course of a few days, but Kathie is two steps a head of Jeff. She figured from the time she met him that Whit sent him to bring her back, and she calls Jeff out on it one moonlit night.
Jeff admits Whit sent him, but at this point the two are in love with each other, so Jeff can’t bring himself to return her to Whit and certain death. Kathie admits to trying to kill Whit, but denies she took his money. She pleads for Jeff to run away with her, and like a sap, he agrees.
The day the two are going to leave, Whit and Stefanos arrive in Acapulco to check up on Jeff. He claims that Kathie skipped off to Chile before he arrived, and is giving Whit back his money because he failed in his task, but Whit refuses. Nobody quits Whit, and he orders Jeff to continue looking for her.
Instead of heading further south, Jeff takes Kathie to San Francisco, and they live there for a while, but one hapless day at the racetrack, Jeff’s old partner, Jack Fisher, still smarting from Jeff’s disappearance and the loss of his $5000 payday, spots the two. Jeff realizes that they are in trouble, and the two lovebirds split up.
Fisher pursues the two, and one day, after Jeff gives Fisher the slip, Jeff drives out to the woods to meet Kathie at her cabin. He’s able to show up too because he’s been following Kathie too. Fisher demands hush money from them, so a fistfight breaks out between the two former partners.
However, Kathie breaks up the altercation when she shoots Fisher dead, and then leaves the scene. Jeff buries the body, and returns to Los Angeles where he’s been hiding out, but before he leaves the cabin, he finds Kathie’s bank book which reveals she made a deposit of $40,000; the same money she denied stealing from Whit.
The flashback ends as Jeff and Ann arrive at Whit’s mansion on the lake. Jeff tells Ann he will return to her, and she drives away. Inside, Whit and Jeff exchange tense pleasantries. When Kathie appears in the room, Jeff’s taken aback. With nowhere to run, Kathie returned to Whit shortly after killing Fisher, and told him everything that happened.
Whit now informs Jeff that the only way to square thing up with him is to do one more job. Whit claims his lawyer, Leonard Eels, the man who helped him dodge millions in taxes, is now demanding $200,000 in hush money, or he will give the Feds Whit’s business records. This would surely land Whit in prison for 10 years for tax evasion. So, Whit wants Jeff to get those records, but Whit knows this is just a ruse to set him up.
However, he has no choice to do what Whit demands, and he heads off to San Francisco to meet Eel’s secretary, Meta Carson. Carson is secretly working with Whit, and she takes Jeff to meet Eels’ apartment suite to meet him. There, the three share a drink, and Jeff realizes his fingerprints are now are the scene of what he presumes will be a murder.
He’s right. He returns sometime later to prevent Eel’s death, but arrives too late. Someone killed the attorney while he was gone. Jeff hides Eel’s body, and then he heads to a local club Whit owns where he grabs Whit’s business records from Eel’s stolen briefcase.
He heads to Kathie’s place in town to look around while she’s out. When she unexpectedly returns, he hide in another room, but overhears her impersonate Meta Carson. She calls the office at Eels’ complex asking them to check on him because she’s worried that she hasn’t heard from him. The plan is such that the man working will find Eel’s dead body, and call the cops; framing Jeff for the murder after finding his fingerprints there.
When the man calls Kathie back, and tells her nobody was there, she panics, and calls Joe for help. Jeff appears, and confronts Kathie. Kathie claims she gave Whit a signed affidavit that Jeff killed Fisher, and when Eel’s murder is reported in the morning, he will be wanted for two murders.
As Jeff flees to the mountains of Bridgeport, Kathie orders Stefanos, without Whit’s knowledge or approval, to follow The Kid back at the town, and then kill Jeff. When The Kid drives to a narrow canyon with ragged cliffs, Stefanos arrives too, and spots Jeff. Stefanos aims to shoot Jeff, but right as he does, The Kid hooks him with his fishing line, and Stefanos loses his balance, and falls to his death.
Jeff then returns to Whit’s mansion at Lake Tahoe, and tells him all about Stefanos’ death, and Kathie’s double-cross. He tells Whit to make Stefanos’ death look like a suicide, and leave a note that he did it because he feels guilty for killing Eels; thus removing the frame from Jeff.
Then he offers to exchange Whit’s business records for Kathie’s affidavit implicating him in Fisher’s murder and $50,000. Whit agrees to the deal.
Thinking he’s now free from this ordeal, Jeff returns to visit Ann, and he tells her that he loves her. The next day, Jeff returns to Lake Tahoe, but finds Kathie killed Whit. She tells Jeff he has no choice now but to run off with her and Whit’s money, or he will be implicated in all three murders.
Jeff agrees to leave with her, but as Kathie packs her things to leave, Jeff calls the police. The two drive off to safety, but when they come to a police roadblock, Kathie realizes Jeff betrayed her too, and she shoots him dead. She then takes aim at the police, but they shoot and kill her.
Later, the news of Jeff’s death reaches Bridgeport. Jim, still in love with Ann, offers to take her on a ride. They don’t even have to talk, but she says no. Ann then walks across the street to Jeff’s gas station where The Kid sits. She asks him if Jeff planned on running away with Kathie. The Kid lies to her, and nods his head. Heartbroken, Ann returns to Jim’s car, and she drives off with him. The Kid smiles, and salutes Jeff’s name on the station’s sign.