Susan raises a window shade at the motel to reveal her face, obliterating the window's reflection of the desert landscape from outside. She watches as hot rods arrive carrying a gang of teens. Although Vargas believes Susan is safe at the motel, she is quick to be victimized and persecuted.

Meanwhile, Vargas begins an investigation of his own, determined to show how Quinlan planted the dynamite. The camera films him driving with Schwartz as his passenger - careening at high speed through the town's streets. The perspective is through the windshield with the scenery behind them moving rapidly away. Plotting how to capitalize on Quinlan's weaknesses, Vargas and Schwartz consider examining dynamite purchase records and searching Quinlan's Texas ranch outside of town: ("We must show where Quinlan himself got the dynamite").

In the sequences of Susan's terrifying experiences with the juvenile gang - tough, leather-jacketed Mexican hotrodders including 'Pancho' - they first harrass her by playing loud rock 'n' roll through the concentric loudspeaker/intercom on the wall so that she can't sleep. Then, they take over the office switchboard, cut off her phone calls, and terrorize the night attendant who had returned. The night attendant at the motel realizes that the black-jacketed group that has commandered the motel office and switchboard are sons of Grandi - sent there by Grandi - under Quinlan's orders.

At a bar, Grandi pours a double bourbon for ex-lush Quinlan. With lecherous anticipation, Grandi carries the two drinks from the bar to Quinlan's table. Grandi suggests that they drink as "partners" to their "little arrangement" to frame Vargas - "Maybe with our little deal, we can hurt him [Vargas]." Quinlan has already downed half of one glass before he realizes what he has done. He looks down to see that he has already started drinking, while blurting out: "I don't ....[drink]." Grandi turns and orders two more double bourbons from the bartender, clearly in charge and filling the frame over Quinlan as the camera pulls back: "Make 'em nice and big." Grandi has also turned on the jukebox (it serves the same function as the pianola music) and bends over a drunken Hank - off the wagon again. [This is the first time that Quinlan's bulk appears smaller - symbolic of his weakened state.]

In an extraordinary tracking shot, the camera follows a group of men (the chief of police Gould (Harry Shannon), DA Adair and Al Schwartz included) across a Mexican street, and into Vargas' hotel lobby where they greet Vargas, and then proceed into a cramped elevator that rides up a few levels. Vargas, who has left the group in the lobby to walk up because there isn't room in the tiny elevator, suddenly reappears at the elevator door on the second floor when it opens. During their ride up, the officers are concerned that a Mexican may bring "criminal charges against one of the most respected police officers in the country. That's what it boils down to." In the privacy of his hotel room, Vargas shows them the document (from the Department of Records) that may incriminate Quinlan, initiate "criminal charges" and prove that he planted the dynamite - a record of his purchase of seventeen sticks of dynamite from Hills Hardware in Los Robles. But the fact that Quinlan purchased dynamite may only be simple coincidence: (Adair: "Quinlan needed dynamite for work on his ranch").

At the Mirador, Susan is terrorized by a voice on the other side of the wall. To scare her, a strange voice tells her that her room is to be entered with the master key and that the threatening gang may drug her with "marijuana," "Mary jane," and a "mainliner." The psychopathic, manly/butch, lesbian gang leader (Mercedes McCambridge) promises: "The fun is only beginning."

Faithful best friend and partner Menzies finds Quinlan, now soused after a bar-hopping journey through half-a-dozen Mexican bars. He warns that Vargas is at his Mexican hotel across the street and convincingly speaking to other officials of the evidence he has found of Quinlan's frame-up: ("Vargas is telling the Chief and the D.A. that you planted that dynamite") - he warns that it is no time to get drunk. Quinlan believes that Sanchez was a foolish killer to use dynamite for murder. They talk about the strangulation murder of Quinlan's wife with a "binding cord" that employed a more silent, clean method: "Clean, silent...That's the way my wife died...You don't leave fingerprints on a piece of string." He tells Menzies that strangulation is the "smart way" to kill a person and not be detected.

In a scene displaying Quinlan's human side to Menzies, he drunkenly recollects his wife's brutal murder in a packing plant by strangulation when he was a "rookie cop" 30 years earlier covering the case. She was murdered by a "half-breed," and because there was no evidence to prove the man's guilt, the suspect went free. Quinlan never found the killer: "I followed around after him, ate my heart out trying to catch him, but I never did." But then justice was attained when the killer died: "Then in some mud hole in Belgium, the good Lord done the job for me." He boasts about his fanatical, ruthless approach to law enforcement: "That was the last killer that ever got out of my hands."

[Note: Ever since, Quinlan developed and maintained a hatred for Latinos, and habitually planted evidence and framed suspects to assure convictions.]

Believing that Vargas is fighting "dirty," Quinlan crashes into the hotel room where Vargas is meeting with the DA and Chief of Police, and accusing the policeman of planting evidence:

There are all kinds of policemen, sir. I don't have to tell you that. A few take bribes...Most are honest, yes, but even some of the honest men abuse their power in other ways.

The DA defends Quinlan's record as an "honest cop." In a confrontational face-off, Quinlan derides the principled, admirable Vargas for accusing him of being a corrupt cop:

Quinlan: Our friend Vargas has some very special ideas about police procedure. He seems to think it don't matter whether killers hang or not, so long as we obey the fine print.
Vargas: Captain, I don't think a policeman should work like a dog catcher in putting criminals behind bars. No! In any free country, a policeman is supposed to enforce the law, and the law protects the guilty as well as the innocent.
Quinlan: Our job is tough enough.
Vargas: It's supposed to be. It has to be tough. A policeman's job is only easy in a police state. That's the whole point, Captain - who is the boss, the cop or the law?

[One of the film's main themes is expressed here: "Who's the boss, the cop or the law?" Quinlan acts as both judge, jury, and executioner.]

Vargas informs Quinlan that he knows that he purchased seventeen sticks of dynamite, and that his ranch's hired hand had used about fifteen sticks of the dynamite. Quinlan, who had just picked up a delicate pigeon egg on the window ledge (where earlier, the pigeon had been frightened by Susan), crushes the egg in his enormous hand when he realizes that the Mexican is pulling the noose tighter around his neck: "You been spyin' out at my ranch? A foreigner?" [Note: The remaining two sticks were the ones planted in the shoebox, according to Vargas.]

Quinlan throws down his badge, angered at the implications of the Mexican investigator's questions. A thirty-year veteran of the force with his integrity impugned, Quinlan lumbers down the hotel hallway:

30 years of pounding beats and riding cars, 30 years of dirt and crummy pay. For 30 years, I gave my life to this department. And you allow this foreigner to accuse me. Answer, answer, why do I have to answer him? No sir! I won't take back that badge until the people of this county vote me back.

The Chief of Police vows his support for Quinlan and reprimands the D.A. for backing up Vargas:

I don't want ever to see that man in headquarters for any reason at any time! Now, you backed him up!...You stood by while he impugned the integrity of Captain Quinlan. Do you realize what Vargas has done? He's smearing hundreds of fine men!

The D.A. is forced to back up Quinlan, and even demands an apology from Vargas. Vargas refuses with sarcasm: "Would you like me to get down on my knees?...Mr. Adair, I won't give you the chance to test your authority in this matter." However, Vargas isn't allowed to pursue his official investigation of Quinlan any further. Left alone with Schwartz, Vargas asks him where he could locate the records of Quinlan's "old cases", and he goes off to investigate them with Schwartz.

As Quinlan gets back in the hotel elevator, his faithful partner Hank Menzies returns his badge to him. Quinlan attacks with a counter-accusation of his own toward narcotics investigator Vargas. To defend himself, he proposes a solid hunch that Vargas is using his position to supply his wife with narcotics ("mixed up in this dope racket himself"), thereby implicating Vargas' "young wife" as an addicted junkie:

He's a drug addict. He's got that young wife of his hooked too, but good. If I hadn't seen that hypodermic myself...That's how come he happens to imagine all those crazy things. It's typical. What that wife of his was doing on that dive on skid row. Both a couple of junkies. Course he's using the job as a cover-up.

Meanwhile, Vargas enters the Los Robles Hall of Records with Schwartz to examine the records of Quinlan's past cases. Schwartz predicts that he may lose his own job by helping Vargas, and have to go back to his "private practice," and that Vargas has a very long, uphill battle to "solve the murder and also prove that the idol of the police force is a fraud. Amigo. You've got your work really cut out for you."

In a horrifying scene back at the Mirador Motel, the juvenile drug dealers continue to terrorize Susan and creepily break into her room in the motel. Instead of reaching for her husband's revolver, she throws herself on the bed where she is surrounded. They crouch over the bed, preparing to hold her down and 'rape' her. (A fish-eye closeup of Pancho's distorted face shows him flicking his tongue out like a snake.) The hideous faces of the hot rod gang members stare down at her, filmed from her perspective, as the lesbian gang leader chillingly asks: "Lemme stay. I wanna watch" - a voyeuristic invitation for the film audience as well. They grab Susan by her arms and legs as she cringes on the bed, struggling and screaming. [It is all part of Grandi's and Quinlan's plot to discredit Vargas by framing his wife on drug charges and accusing both of them of being drug-users.] When the door in the hotel is shut, it is presumed that she is either raped or shot up with drugs behind the door.

Another door opens, in a clever transition, in the Hall of Records, where Menzies locates Vargas doing research. Menzies, who has devotedly worshipped and obeyed his hero Quinlan for many years, is gradually disillusioned and made to see that Quinlan is a dishonest cop. Vargas skillfully pieces together evidence that Quinlan framed suspects by repeatedly and ruthlessly planting evidence for Menzies to discover: (e.g., an axe, dentures): "It's all there." Ashen-faced and beginning to feel pangs of conscience, Menzies drops his head onto his fist, resting it on the table: "Sure. You can smear him. Ruin his whole life's work. Vargas, I-I don't even know what he is. That's what you've done to him....He's on an important case and he's disappeared. Good and drunk probably." Menzies can only bemoan the fact that Quinlan, as a result of Vargas' investigation, has returned to drinking after twelve years off the booze.

In a tense scene in the dark motel office and then under the outdoor night sky, Vargas begins a frantic search at the Mirador Motel for Susan by cross-examining the night attendant who is himself terrorized by the questioning. He learns that she is no longer at the deserted and dark motel, when the night manager speaks of the "terrible brawl" and "one of 'em wild parties" in Cabin No. 7, Susan's room. Vargas appears somewhat oblivious to what has happened to Susan, and only becomes incensed when he discovers his briefcase with his gun missing. The nervous attendant mumbles and babbles more nervously and incoherently under the pressure, screaming: "I'm gettin' out of here" after finding a leftover joint in the abandoned, cluttered room. The attendant skitters hysterically across the landscape and clings to a bare, windblown tree, confessing that the hotel belongs to Grandi and that the hot-rod gang can be located at the Rancho Grande night club.

As part of the Grandi plan, Susan has been kidnapped and brought unconscious to a rundown room in Grandi's Ritz Hotel - and left half-naked on a bed. At the Ritz Hotel, Grandi learns from hired thugs that after they brought her to the room, they left reefer stubs strewn around, blew smoke into her clothes and "put on a good show to scare her." Although she wasn't actually raped or drugged, Grandi hopes she will awaken and "think maybe something really did happen."

Quinlan, who had temporarily joined Grandi's side to help him frame Susan, now begins to fear that the cowardly Grandi may betray him. To cover up his involvement in the plot, Quinlan has a rendezvous with Grandi in the claustrophobic, rundown hotel room in the city where Susan is located. The only light in the room is from the jittery electric and neon lights flashing and pulsating from across the street. In a close-up, Quinlan draws on black gloves (the foreground image of one of the gloves covers the face of Grandi in the background). He pulls out Vargas's gun (taken from Vargas' briefcase in Susan's motel room), and forces Grandi to telephone the police station to notify Menzies that authorities can find a drugged-up (and framed) Susan in Room 18 of the Ritz Hotel ("The way I hear it, things got a little outta control. Don't be surprised what they find"). Quinlan also learned that Sanchez hasn't "broken" during harsh interrogations (seen in the background behind Menzies).

In a violent, sexually-tinged sequence, Quinlan locks the door of the bedroom and moves ponderously and inexorably toward a terrified Grandi who scurries about the locked room trying to escape. To draw attention and possibly prevent the impending murder, Grandi desperately climbs up to the window above the door and smashes it. Quinlan drags him down, rips off half of Grandi's clothes, and knocks off his "rug" hairpiece. They struggle over the brass bed where a sweating and semi-unconscious Susan lies groaning and writhing, rolling her head back and forth on the bed - lending an orgasmic, climactic tone to the scene. Quinlan conceals his own involvement by strangling the gurgling Grandi with one of Susan's stockings - using his immense size to hold him down. The dead man's face is horribly distorted in death as he falls on the bed frame immediately over Susan's face. [As symbolic revenge, Quinlan uses the same method of murder that was used on his wife. With Susan as a 'surrogate wife,' he acts out the defense of his own brutally-murdered wife by strangling her assailant.] As he leaves the room after utilizing a "smart way to kill", Quinlan makes a fatal mistake - tipped off by a closeup of the sign on the back of the door:

Stop, Forget Anything, Leave Key at Desk.

He leaves his cane at the scene of the crime (a subtle reference to Welles' own Citizen Kane character.)

Moments after the murder, when Susan revives and opens her eyes, she sees Grandi's nightmarish face staring at her from above - his dead tongue sticking out of his mouth. An almost-naked Susan then struggles onto the fire escape from the room where she screams for help. Racing to town from the Mirador, Mike appears in his car frantically searching for Susan, but is the only one who fails to see her on the fire escape high above the crowd gathered in the street outside the hotel, and waving toward him. Unheeded, Vargas searches for her in the town's Rancho Grandi nightclub where the Grandis are often found. Losing all control (and echoing Quinlan's own ruthless methods when his wife was endangered), he goes on a rampage. He pounds Pancho's head into the jukebox, and beats up other gang members. He picks up one of them and throws him down the full length of the bar, as he shouts out disavowal of his profession:

Listen, I'm no cop now. I'm a husband. What did you do with her? Where's my wife? My wife?

The place is smashed to pieces during the fight. The struggle is broken up by police, and Vargas is told by Schwartz that his wife has been picked up by the vice squad and is held in jail. Schwartz explains to Vargas that Susan has been charged with murder: "They found her at the Hotel Ritz, half-naked on one of the beds, drugged. There were reefer stubs and a heroin fix...Vargas, the charge isn't just possession of narcotics...Murder." The camera zooms in on a large close-up of Vargas' face on the right of the screen, losing focus as the picture blurs and goes black.

Immediately, the screen opens on a traveling shot down the corridor of the Los Robles police headquarters jail. Vargas runs to Susan's cell in the jail - she has been charged with possession of drugs and the murder of Grandi. Outside her jail cell, the Coroner (a cameo by Joseph Cotten) explains how authorities found "evidence of a mixed party...articles of clothing, half-smoked reefers, needle marks." [Note: The unusual impression is made that it is possible to 'mainline' marijuana.] Vargas is righteously incensed and outraged at the trumped-up charges and frame-up of his wife: "This whole setup stinks! Who the hell does Quinlan think he is, hanging a murder rap on my wife?" Lying on a jail cot, Susan begs her husband: "Take me home!" and "Don't go!"; however, Vargas again abandons Susan to pursue justice after assuring her: "I'm right here, Susie. It's all right."

Menzies takes Vargas aside, knowing that Susan is not guilty. From under a blanket, he unwraps and shows him Quinlan's cane - left in the hotel room where Grandi was strangled: ("I found it in the hotel room....With Grandi's body"). The evidence found at the murder scene decisively implicates the police detective in the crime.

Vargas moves ghostlike outside Tanya's window, locating Quinlan in Tanya's parlor with the pianola playing. In his second visit to Tanya's place, the aging, weakened cop sits in a stupor in front of a defeated bull head on the wall - with toreadors' spears in him.

The disillusioned partner Menzies is persuaded to illegally trap Quinlan - he will destroy his master by being wired with a microphone and transmitter under his coat while Vargas records their dialogue and a confession of guilt. Betraying the law and using Quinlan's own form of dirty tricks to spy on him, Menzies agrees to lure Quinlan into a confession of illegal actions to defeat him.

Before leaving town with his wife (Schwartz has helped with preparations at the border), Vargas learns from Menzies that Susan has been declared healthy and can travel: ("The kids were all faking...They didn't give your wife any real dope. The doc says it was only that truth stuff"), but Vargas is resolutely determined to clear his wife's name: "How can I leave here until my wife's name is clean? Clean!"

Vargas' plan is to monitor and tape Quinlan's and Menzies' conversation as they walk alone in a desolate place to expose Quinlan's moral corruption: "I've got to get the truth from Quinlan, on tape." Although Vargas admits using evil means to entrap Quinlan: "I hate this machine, spying, creeping...," he proceeds with his plan to bug Menzies. Vargas has won Menzies over to his side, although the loyal cop still feels a twinge of betrayal:

Hank was the best friend I ever had...And who made me an honest cop? Hank Quinlan...I am what I am because of him.

In Tanya's nearby brothel, a drunken Quinlan asks for his fortune to be read, with the help of tarot cards:

Quinlan: What's my fortune? You've been reading the cards, haven't ya?
Tanya: I've been doing the accounts.
Quinlan: Come on, read my future for me.
Tanya: You haven't got any.
Quinlan: What do you mean?
Tanya (warning): Your future is all used up. Why don't you go home?

In the long run, her prophecy proves to be right.

The gripping climax of the film is known for its remarkable, stylish camerawork, editing, and inventive use of sound. Menzies lures an inebriated Quinlan out of the noisy parlor so that a recording can be made. Menzies and Quinlan walk through the desolation and filth of a section of canals in the town, with oil derricks, rhythmically-pumping oil pumps, and metallic tanks. [The film viewer hears the conversation from two sources: the characters themselves and through the speaker on Vargas' receiver speaker.]

Suspense is built when Quinlan accuses Menzies of becoming "chummy" with the Mexican, and asks about what he is carrying around and wearing. Menzies immediately assumes Quinlan knows of the hidden wires - until Quinlan refers to the self-righteous "halo" he is wearing: "Looks real pretty on you, Pete. Pretty soon, you'll be flapping your wings like an angel." Quinlan warns Menzies about the problems presented by Mexican law enforcement official Vargas:

Look out. Vargas'll turn you into one of these here starry-eyed idealists. They're the ones making all the real trouble in the world. Be careful, they're worse than crooks. You can always do something with a crook.

At one point, Menzies accuses Quinlan of turning into a crook: "You're the one that should be careful, Hank, dealing with crooks...Sometimes you can turn into a crook yourself. Look what happened with Grandi," but Quinlan refuses to be called a crook: "Partner, nobody ever called me a crook." The nightmarish images of the city include grotesque, dark pumping oil derricks, garbage heaps, and seedy streets. Looking at one of the oil pumps hypnotically "pumping up money, money," Quinlan self-righteously speaks of the materialistic ambitions he could have had as a greedy, corrupt cop:

Don't you think I could have been rich? A cop in my position. What do I have...after thirty years, a little turkey ranch - that's all I got. A couple of acres.

Quinlan blames everything on Vargas: "This Mexican comes along, and look at the spot he puts me in!...I blame Vargas for everything." Quinlan is maneuvered into talking about the many convictions he has been responsible for over the years:

Menzies: Defend yourself, Hank. You murdered Grandi.
Quinlan: I left my cane by his body. That was sure crazy....
Menzies: Grandi was strangled.
Quinlan: Grandi was a crook.
Menzies: You're a killer, Hank.
Quinlan: Partner. I'm a cop.
Menzies: Yeah, yeah, yeah. Drunk and crazy as you must have been when you strangled him. I guess you were somehow thinking of your wife, the way she was strangled.
Quinlan: Always thinking of her, drunk or sober. What else is there to think about? Except for my job, my dirty job.
Menzies: You didn't have to make it dirty.
Quinlan: I don't call it dirty. Look at the record....All those convictions.
Menzies: Convictions, sure. How many did you frame?
Quinlan: Nobody.
Menzies: Come on, Hank. How many did you frame?

Although he doesn't admit to framing his suspects, he asserts that all his suspects were guilty: "Nobody - nobody that wasn't guilty, guilty, guilty. Every last one of them - guilty." To him, "faking evidence" is equivalent to "aiding justice." As they talk and walk on a canal bridge above his head, Vargas clambers after them, wading through the black gutter water of the canal below with a portable recorder. Quinlan discovers the subterfuge and set-up trap when he hears the sound of the speaker echoing off the bridge. His "game leg" starts to talk to him, and he wonders if Vargas is "tailing" him. Learning of the betrayal, he finds the hidden "bug"/microphone on Menzies. Menzies hands over Vargas' gun (heard on the recording apparatus' speaker) and Quinlan shoots his best friend Menzies with Vargas' gun.

As Menzies sinks down onto the cold, dark street, Vargas comes into view behind him. Realizing he has Menzies' blood all over his hand, Quinlan dashes for the slimy gutter water to wash it off, and then falls back onto a heap of garbage. A single tear is shed by Quinlan. Vargas tells Quinlan he has finally been caught committing murder, but Quinlan expects to frame Vargas and blame him for Menzies' death:

Vargas: Well, Captain, I'm afraid this is finally something you can't talk your way out of.
Quinlan: You want to bet? You killed him, Vargas.
Vargas (weakly): Come on, now. Give me my gun back.
Quinlan: You don't understand me. You killed Pete. The bullet is from your gun.
Vargas: Do you think anyone would believe that?
Quinlan: They always believe me. Anyway, they'll never believe I killed him.
Vargas (asking for the gun pointed at him): The gun?
Quinlan: You're resisting arrest.
Vargas: How could you arrest me here? This is my country.
Quinlan: This is where you're gonna die.

As Quinlan turns his gun on Vargas and is about to kill him as a suspected murderer, Menzies who is still alive but mortally wounded, fires a fatal shot that hits Quinlan. [Note: Ironically, Quinlan's most faithful worshipper and accomplice kills him.] Schwartz arrives with Susan in a car and rushes to the scene. Vargas briefly informs Schwartz: "That's Menzies. He's dead" - an inadequate eulogy for the most innocent and heroically-sacrificial of all the characters. Vargas rushes to his wife and hugs her in their car. Schwartz plays back the tape recording of the conversation. As Quinlan expires and listens to his own confession, a close-up of his sweating, contorted face appears:

(On the tape)
Menzies: All these years, you've been playing me for a sucker. Faking evidence...
Quinlan: Aiding justice partner.

Vargas promises his wife: "It's all over, Susie. I'm taking you home. Home." Cleared of the drug charge, they speed away to a safer, more secure place. Tanya runs across the bridge toward Quinlan, as the tape continues to play his confession.

(On the tape)
Menzies: How many did you frame?
Quinlan: Nobody that wasn't guilty. Guilty...

At the tape's climax, Quinlan stands up, and hears the gun shot on the tape. He looks up at the dead body of Menzies on the bridge above him and mumbles to his treasonous partner who betrayed him:

Pete. That's the second bullet I, I stopped for you.

[The first bullet was when he saved Pete's life many years earlier - the cause of his limp.] When Quinlan loses his balance, his large, flailing body falls backwards into the oily, dark water. As he flounders and dies like an animal in the shallow canal, Tanya is left to watch Quinlan's body floating in the muddy water.

Tanya is told by Schwartz that Sanchez had been framed, but had also confessed to the car bombing crime; according to Schwartz, Quinlan's "famous intuition" had been right all along:

His famous intuition was right after all. He framed Sanchez. But he didn't even need to. The kid confessed about that bomb. So, it turns out Quinlan was right after all.

Schwartz asks if Tanya liked Quinlan, and she responds: "The cop did. The one who killed him. He loved him." Schwartz reiterates how Quinlan was a good cop who often knew - through intuition - who was guilty. But the detective was also a "lousy cop" when he served as the law's judge, jury, and executioner:

Schwartz: Well, Hank was a great detective all right.
Tanya: And a lousy cop.

When asked: "Is that all you have to say for him?" the cynical and world-weary Tanya eulogizes Quinlan as she looks wryly at his body lying and floating away in the dirty water - providing a famous epitaph (above the sound of pianola music):

He was some kind of a man. What does it matter what you say about people?...Adios!