In a voice-over, reporter Harry Mitchell, William Gargan, wonders how a string of sinister events could all happen within a single day, a montage of shadowy faces flashing as he muses about people who seem to have “come out of nowhere and be gone again in one day.” The scene shifts to hospital corridors where Allen Pierce, George Anderson, the top man of Washington’s political columnists, lies recovering after promising his readers explosive information about the so-called Argyle Album that could ignite a scandal bigger than Teapot Dome.
At Pierce’s side sits Elizabeth Court, Barbara Billingsley, his secretary who remains composed even as a doctor frets about Pierce’s fragile condition. Pierce, growing gravely ill, explains to Mitchell—who has come to learn more—that the Argyle Album is dangerous information he felt compelled to share with somebody. The photostat of the album’s cover surfaces, and in a sudden turn, Pierce’s strength collapses as a fatal illness takes him. A physician, nurses, and Mitchell scramble to understand what happened, but the room’s tension tightens when a scalpel is found buried in Pierce’s chest, a clue that casts suspicion on the hospital staff and Mitchell alike. When the room’s order is restored and Pinky, Alvin Hammer, the photographer, is found to have never left Pierce’s side, the police grow wary, and Mitchell makes a hasty exit.
Determined to uncover the truth, Mitchell returns to Elizabeth Court’s apartment, where he overpowers her and searches for the album. Though he fails to locate it, he does recover Pierce’s address book with five names and, in a bold move, mails Pierce’s photostat of the album cover to himself for safekeeping. A heavyset man with a panama hat—Panama Archie, Jack Reitzen—arrives brandishing a swordstick, but Mitchell defeats him and locks the intruder away in a closet as Elizabeth looks on, bound and gagged. Before leaving, Mitchell lets in another woman who claims to be Elizabeth’s friend, only to flee again when danger closes in.
That visitor, Marla, Marjorie Lord, tracks Mitchell to a friend’s vacant apartment, revealing that his face has already filled every newspaper and offering money for the Argyle Album. Mitchell insists he doesn’t even know what the album is, and Marla introduces three men—Winter, Hobrey, and Scanlon—who are part of her party. Mitchell endures a brutal beating as Winter explains how he smuggled the album out of Europe after World War II as collateral for a future payoff. When Marla explains the album’s value—information about American businessmen who collaborated with the enemy—Mitchell understands that the album’s power lies in its potential to blackmail. After Marla lets him go by feigning concern, Mitchell escapes down the fire escape and slips into yet another apartment that belongs to his former neighbors, the Rubins, where Mrs. Rubin offers a brief moment of solace before he slips away.
Mitchell then heads to a dingy Wooster Street shop run by Jor McBrod, Alex Frazer, a fence who currently holds the album and had Pierces’s supposed contact. A tense confrontation ends with McBrod wounded and panama Archie wounded as well, and McBrod clings to life long enough to reveal nothing about the album’s current location. Mitchell, left with little more than questions, decides to turn himself in to Lt. Samuel Sampson, Ralph Byrd, who confirms Pierce died of poisoning rather than the knife wound, and Pinky’s death is attributed to another fatal stabbing. The police remain skeptical of Mitchell’s story, but they also agree to shadow him as he moves forward, leaving him with a quiet, precarious freedom.
With night closing in, Mitchell visits Marla at her hotel, where she hovers between fascination and treachery, attempting to extract details about McBrod’s connections and the album’s whereabouts. Marla’s shifting testimony only deepens the mystery, but she asserts that Winter’s gang still knows nothing about the album’s location; she hints that Panama may have been working for someone else entirely. Mitchell moves next to Scanlon’s apartment to intercept a phone call from Winter, then returns to McBrod’s shop where Winter and Hobrey lie in wait. A gunfight erupts, and Mitchell is wounded by Hobrey’s shot, forcing him to take refuge in a locked storage area. Hobrey, poised with an acetylene torch, closes in, and Mitchell reveals a crucial insight: two “big shots” named in the album are chasing the truth, one connected to Pierce’s doctor and Panama, the other the man who has been posing as the real Winter.
As Winter closes in to burn Mitchell out, the reporter proclaims that he now holds the Argyle Album’s cover in his memory, using Pierce’s photostat to identify his rival. He warns Hobrey that the fake Winter intends to double-cross and kill him. In a final, brutal twist, Winter shoots Hobrey, who still manages to kill Winter before collapsing himself. Mitchell realizes that McBrod must have mailed the album to Pierce, and that Elizabeth Court now holds it in a briefcase at the airport. Mitchell pays Court five hundred dollars for the case, while Marla appears and the two discuss the night’s tangled web, with Mitchell expressing a sense of duty to reveal the album’s truths to the public. Marla frames their partnership as something more, but she also draws a gun, only to be outmaneuvered as Mitchell hands the briefcase to Lt. Sampson, who has shadowed the exchange. With the case secure, Sampson returns it to Mitchell, who feigns ignorance and walks away, leaving the Argyle Album’s fate uncertain but the truth tantalizingly close to exposure.
