Jim drives along a highway on a sunny California day, following a man in a cowboy hat driving an old, robin's egg blue pickup truck. The man pulls to the side of the road and gets out. He walks through a gap in a weathered wire fence, across a field of tall grass towards the water. Jim turns his car around, looking for a place to park. He stops, then opens his trunk, there trading his dust colored sport coat for a fishing rod. At the fence gap he sees Cowboy Hat has crossed most of the field. Cowboy Hat reaches the rocky edge of the beach and drops from view. Jim hurries then, arriving at the top of the slope moments later. The man has vanished! There are only rocks, sand, beach scrub, and the cries of seagulls. And, concealed beneath the lip of rock, a narrow sea cave.
Jim trots to and through the cave to another section of beach. There is a woman reclined on a beach towel here, reading. Jim asks her if she saw Cowboy Hat. He has some difficulty with her; his questions seem to amuse her. But finally she reveals that she did not see the man.
Moments later, Jim walks up a beach road. A red Mercedes convertible appears; behind its wheel is the beach woman. She apologizes for her odd behavior, explaining that Jim took her by surprise. She says she was reading a book and Cowboy Hat could have passed her, but she doesn't think it too likely. She asks after Jim's profession, and he tells her that he sells greeting cards. Then, she tells him where to find her apartment and invites him to visit her for a drink.
At her apartment, the woman fixes Jim a drink while he glances through “The Social Registry”. She already knows he's not in there; she reads the book because it contains the names of rich people. She hopes to find and marry one. Wryly, Jim notes that at least this means of earning a living is not as seasonal as selling greeting cards. She replies that it's difficult to be “spontaneous and blunt” at the same time. Jim finishes his drink, sets the glass down, and then asks her what's going on: he realizes she didn't invite him to her apartment on a whim.
She admits to nothing, but Jim knows with his money situation that she cannot be seriously interested in him... unless to set him up somehow. That's when his world starts to blur and slide sideways. He asks if the woman doped his drink, but cannot hear her reply. Then he lurches towards the door, and eventually through it into the hallway. Weaving along, he makes it past a few doors and then hits the floor. Just before he passes out, he slips his notebook under the edge of hall runner.
Jim recovers hearing a man's voice ask the woman what else Jim told her. A familiar cowboy hat perches on a nearby desk, and directly in front of Jim's face is the business end of a very large revolver, held by Cowboy Hat. Cowboy Hat wants to know who Jim is and why Jim has been tailing him. Jim identifies himself as Lieutenant Larry Dent of the LAPD, but Cowboy Hat doesn't believe this, since Jim has no gun or ID. About then, Jim realizes Cowboy Hat and his lady have removed his pants!
Jim tells Cowboy Hat – whose name he knows is Travis – that since he wasn't having any luck tailing him, he was planning to just ask him. About what? Jim is investigating the Kirkoff killings, and heard Travis was having an affair with Mrs. Kirkoff before she was killed. Travis asks Jim who his client is, and Jim tells him that's confidential, until Travis waves his hand cannon around again. That draws the client's name from Jim: Larry Kirkoff. Travis swears he wouldn't kill anybody, and especially not Jenny Kirkoff. He thinks Larry Kirkoff killed his own parents, and apparently the cops and the D. A. share this opinion.
Travis and his lady friend finally return Jim's pants so Jim can leave. They again assert that Larry is the killer. Jim reveals that Larry has his own theory, which did not interest either the D. A. or the cops. Jim concedes he may be wasting his time, but...
Travis decides to take Jim for a ride. Jim could make trouble, and Travis plans to make sure that doesn't happen. Jim's mild refusal doesn't move Larry, so on the way out, Jim lights a cigarette, and then flips it through the air. Travis tracks it and Jim takes advantage of the exposed chin to land an uppercut that lays Travis out. Then he demands his camera from Travis' girl and takes a picture of her. As he leaves she adds her voice to the chorus of those who believe Larry Kirkoff killed his parents. She believes Kirkoff hired Jim only to convince the society people that he didn't do it.
Later, Jim reports to Larry Kirkoff against a backdrop of furniture movers and a growling Doberman pinscher, confirming Larry's belief that Travis was having an affair with Larry's mother. Jim offers an opinion. Larry reminds Jim he's paying for observations, not opinions. Jim says he's offering a special this week, and the opinions are free. The opinion is this: Travis doesn't figure as the murderer. Larry's mother was putting money in a bank account for him, letting him train horses... the death of the Kirkoffs stopped all that, so where's Travis's benefit? Kirkoff believes jealousy or a lovers' spat to blame.
Outside, Larry and Jim continue the conversation with Jim's second opinion: Larry still looks better for the crime than anyone else. Larry understands why Jim doesn't charge for his opinions: they're not worth much. He defends that saying that the D. A. never brought him to trial and the police have stopped investigating him. Jim counters that the police have stopped investigating because they're sure Larry is the guilty party, but cannot prove it.
Opinion number three is that Larry is having too much fun redecorating the family home for a man broken up over his parents' death. But Larry says he has to live there now, and he doesn't share his father's Victorian tastes or sensibilities. Jim suggests the move lacks style and then tells Larry he'll send a bill for the time worked. But that won't do. Larry simply asks Jim how much more he wants. He thinks from a bonus of $20,000, Jim will be more motivated to find out who killed the Kirkoffs. Jim knows if Kirkoff killed his own parents, and Jim can't prove it, he'll be a long time collecting. Kirkoff blandly states that his offer stands and he won't bicker about it.
There is one thing Jim might look into: the picture he took of Travis' girlfriend. And since Larry has a darkroom, they can find out if the picture means anything. In the darkroom, Larry watches the picture develop as Jim notes Mrs. Kirkoff was killed with a Tokarev 7.62mm pistol, and Mr. Kirkoff was shot with a 300 magnum hunting rifle at long range – a rifle Larry owned until his was stolen. Larry never reported that theft because he hadn't used and did not miss the weapon. The darkroom walls feature several pictures of Larry with the rifle. Larry says the pictures, taken five years ago, aren't relevant.
Larry knows the woman in Rockford's picture. Not by name, but he saw her once visiting his father's hunting lodge. Just before he got there, his father's car pulled out with this woman at the wheel. At that time his parents were separated, so he figured his father was seeing the woman and wanted to keep that quiet so his mother couldn't use it as a lever during the divorce proceedings. Rockford agrees to check her out.
Jim follows the red Mercedes into the West End Tennis Club, spoofing his way past the gate with a false message delivery line. He skims the club newsletter, noting an article about members Madge and Jerry Green visiting the Greek Isles. He puts down the brochure and walks to a sitting area. The assistant manager has spotted him, and follows him there, asking how she can help him. Jim tells her he is looking for Jerry Green. But Jerry Green is of course not around. Jim identifies himself as an old friend of Jerry's from Chicago, in town on business. Drawing on the article, he uses social engineering to wrangle a guest card from the assistant manager.
Outside, he finds the woman sitting near the courts with a friend named Calvin Carras. Jim acts like an old friend, identifying her as Tonya Baker. They banter, Jim making veiled references to their previous encounter. Jim drives off Carras with a fake insurance salesman's card and a thin pitch. There's candor now; Jim has Tonya over a barrel. He has learned things about her background and could cause her trouble at this club – including an affair she had with Larry's father Charles Kirkoff shortly before Charles' murder.
Tonya wants Jim to tell her want he wants and then leave. He asks her to dinner. She already has a date which Jim demands she break. He wants to ask her questions, to see how she and Travis fit into the Kirkoff killings. Her story is that she loves Cal, and Travis loved Mrs. Kirkoff, and when Larry didn't get tried for the murders they decided to look into it themselves. She's certain Travis didn't murder anyone. Rockford dryly tells her he'll collect her at eight. She doesn't want to go out with him. He's not all that crazy about the idea himself, but he does want Larry to pay him that $20,000, so...
Jim returns home, a beat up trailer on the Malibu shore. His father Rocky waits for him there. As Jim searches for an aspirin to kill his Mickey Finn hangover, Rocky reads him phone messages: someone trying to scalp Los Angeles Rams tickets, and a lady who refused to give her name, but left a phone number. That one intrigues Jim, so he dials back. The woman who answers knows Jim's looking into the Kirkoff killings; she claims she has relevant information and offers to sell it if he meets her at the Sierra Lounge on Wilshire at eight. She tells him how to spot her: she'll wear a red coat and sit in a rear booth. Jim asks Rocky to call a contact at the telephone company who can give him the address attached to the telephone number.
Eight o'clock finds Jim pulling into the parking lot of the Sierra Lounge, where a valet... punches him hard in the stomach! Two other men join in, subduing Jim and hustling him back into his own car. The valet slides behind the wheel and the other men slip in and drive off. Not far away, a man struggles on the ground, his mouth taped, his hands bound and his valet's jacket missing...
On the way, one man makes sure Jim hasn't got a weapon. They pull into a warehouse and another man joins them; the four of them hit Rockford several times just to convince him they're serious. A rough-voiced man speaks from the shadows, offering Jim some advice. He knows Jim is a private eye who has to work, but he also says Jim's client is guilty. Everyone knows this – so how come Jim is trying to prove it otherwise? This guy claims not to care about Larry Kirkoff one way or the other. But if the D. A. reopens the case he might discover a certain real estate fraud. That would cause the man real trouble, and if that happens, Jim will end up in a brass bottle. So Jim doesn't feel too bad about the beating, the man leaves him $200. As they leave the thugs kick out Jim's headlights, darkening the garage. By the flame of a cigarette lighter, Jim finds one of his teeth on the floor...
At the police station, Jim nurses injuries while his friend Dennis Becker scares up the form to record an assault. Unable to find it, he uses a form for murders which is close enough. The way Jim's going, Dennis figures he may need the murder form! Dennis is incredulous when he discovers Jim is working for Larry Kirkoff. Like the rest of the LAPD, Dennis is sure Larry murdered his parents. The police would have had Kirkoff except they couldn't find the rifle and they couldn't put Larry at the crime scene.
All Jim knows about the men who worked him over is that the one who did the talking had a husky voice, possibly the result of getting hit in the windpipe. Dennis will fill out the form and give it to patrol, but tells Jim to expect that nothing will come of it. Naturally, Jim is less than impressed. Dennis has to remind Jim that the police hold him in low regard – it actually cheers them up when Jim shows up with a broken nose. Jim's next request is for Dennis to find out who owns the condemned warehouse where they took him to work him over – he thinks he's got someone worried, and that means these men may have had something more to do with Kirkoff than real estate fraud. Finally Jim agrees to spot Dennis ten points next handball match. For the information, Dennis wants five bucks a point and ten bucks a game, but agrees to two bucks a point and five bucks a game. He further demands Jim tell no one where the information came from, and that Jim share anything he learns so Dennis gets to look like the hero.
Later, Jim pulls up to a club called the Owl 'n Turtle in a rental car. Inside, he scans the room until he finds Tonya, who is chatting up another patron. Jim's an hour late, and she sees he's been fighting – or, as he puts it, catching punches. They move to a table. Tonya finds Jim irritating precisely because he scratches and claws for a living. She admits she went after Charles Kirkoff because he had money; and says she told him that and he understood it. But she also says she wouldn't have stayed after him if she hadn't found him attractive. She further says she'd have married him even without his money – he was one of a kind. Others Jim has spoken to describe Charles as a cold number, but with Tonya he was apparently different.
Jim explains his bad day, then offers a handshake and the idea that they could start fresh. After a moment, Tonya agrees. As neither can afford the Owl 'n Turtle, they soon find themselves at a drive-in. Burgers in hand, they discuss the case. Jim has learned that the condemned warehouse used to belong to a union called the BRW, the Brotherhood of Iron Workers. This was the union Charles Kirkoff mostly negotiated with.
Jim questions Tonya about the time she spent with Charles shortly before his murder at his beach house. Did Kirkoff have any business conversations? Tonya confirms that he had such conversations all the time, and that she got the impression at least part of it was showing off. Next Jim wants to know if Kirkoff ever sent her out of the room before starting such a conversation. He's working the perimeter of a theory he thinks the cops never tried. Tonya can remember two conversations like that. As she left the room she heard Charles ask, “What is it, Muzzy?” The comment stuck with her because she felt Muzzy was an unusual name. Jim remembers a fighter, ten or fifteen years ago, named Muzzy Vinette. Muzzy's poor footwork spelled a short fighting career, but has he found new work?
Some time later Jim, with glasses and a suit, visits the BRW as “J. Rockford”. He speaks to a man acting as a receptionist and claims an appointment, saying he's from Kirkoff Industries in connection with a personal injury lawsuit. He further says he needs to speak to Mr. Dancer personally. The desk man doesn't buy it, and escorts Jim to the elevator, telling him his only way in to see Dancer is to “climb over him”. Jim tries the cigarette flick distraction, which gets him punched across the room to flops onto a couch. It seems the union man has seen that trick a couple of times. Rummaging Jim's pockets, the man finds his private investigator's license. That earns him what he wanted – a visit with Mr. Dancer.
Dancer wonders why he shouldn't have Jim arrested for assault, and Jim explains that his poke at the desk man was only to get him this meeting. Dancer gives him thirty seconds. Jim tells Dancer that what he has to say, Dancer won't want his men to hear. After confirming Jim is clean Dancer sends his men out of the room.
Jim wonders whether Dancer would like learning that one of his men was moonlighting and of course Dancer would not. The man in question? A goon named Muzzy Vinette. Dancer first corrects Rockford, saying that in the public relations era, Vinette is not a goon. He is a labor organizer. Then Dancer tells Jim to get to the point. Jim suggests Vinette might have a gun, and Dancer might know about it, and opines that the gun might be a Tokarev 7.62mm automatic. And further, that perhaps Vinette took an independent contract to kill somebody: Mrs. Charles Kirkoff. Dancer stares for a moment, then asks Jim why he should believe this story. Jim mildly says that in the age of public relations, Dancer can't afford not to believe it. Dancer tells Jim that if he's right he's owed a favor. After Jim leaves, Dancer tells his right hands to go and get Muzzy and any guns he might have, and come back to the union office.
Dancer's men leave the union garage. Jim tails them in his rented machine. This trip ends at a nice suburban rancher. Jim watches from outside for awhile, and then hears a pair of gunshots. A man leaves the house. He's not one of the men sent to collect Muzzy – so he must BE Muzzy. He spots Jim and flees! The car chase breaks a fence and enters a country club over the protests of golfers. Vinette's care dives into a swale as he tries to elude Rockford. There's dust everywhere and the chase enters a sparsely wooded area. Dodging golf carts and complaints, Rockford refuses to give up, finally forcing Vinette into a sand trap where his car bogs down. Fleeing on foot, Vinette catches a sand shovel to the stomach, knocking him down and out and allowing Jim to relieve him of his hand gun.
It turns out Charles Kirkoff hired Fuzzy Vinette to kill his estranged wife. Having proved that, Jim wants his $20,000. But who killed Charles? Jim says he's sure Larry commited that murder – but only that one – when he learned his father had hired his mother's murder. But the cops cannot find the rifle so they can't prove it. Larry is reluctant to part with $20,000, and Jim allows that's reasonable. He's willing to settle for $10,000. Larry instructs Jim to send a bill. Another growl from Larry's perpetually angry dog convinces Jim that he should leave and wait for a check in the mail.
Jim and Tonya drive and discuss the outcome. She doesn't believe Charles hired a man to kill his wife; it's not like the man she knows. She wonders if it was because of her. Jim says it was because his wife was about to ruin his reputation and pick him clean in divorce court, and advises her not to make herself the heavy. But what irks Jim is the notion that Larry's going to get away with murder, unless someone who cared for Larry's father took an interest in the case. They haggle a bit before she agrees to pay Jim $150 a day to look into who killed Larry's father. But on the way into the Owl 'n Turtle, the evening edition tells the story. A full width headline says Larry Kirkoff Admits Killing Father. Larry wasn't trying to get away with anything. He was just waiting for Jim to prove he was right about his father's crime, so he could give himself up. Tonya fires him – with no income he takes her to a hotdog stand for dinner instead.