As Philip Marlowe, portrayed by Humphrey Bogart, arrives at the lavish estate of General Sternwood, known not only for his wealth but also for his cunning nature, he finds himself summoned to resolve a troubling issue that has left the family in distress. The General's rebellious daughter, Carmen, is caught in a blackmail scheme orchestrated by Arthur Geiger, a dubious bookseller adept at exploiting the Sternwoods' darkest secrets. This act of extortion unfolds as the latest incident in a long-standing saga, which originally ignited when Joe Brody aimed to extract hush money from the family.
As Marlowe delves into the intricate dynamics of the Sternwood family, he stumbles deeper into their convoluted relationships. Vivian, the older sister trapped in a passionless marriage with Rusty Regan (played by Jack Bailey), seeks Marlowe's counsel regarding her husband's mysterious disappearance. Yet, Marlowe maintains a stoic silence, his poker face reflecting his commitment to professionalism.
Marlowe's investigation leads him to Geiger's shady bookstore, where he encounters Agnes, the enigmatic clerk, whose presence adds to the underlying suspicion. A stakeout at Geiger's residence uncovers a horrifying scene: Geiger lies dead, and Carmen is found drugged and unconscious, sprawled in front of a vacant camera. After taking Carmen back to safety, Marlowe is dismayed to discover Geiger's body has inexplicably vanished upon his return.
The following day, the police reach out to Marlowe with troubling news regarding a car accident involving the Sternwoods' chauffeur. His body is discovered in a vehicle that had plunged into the sea. Meanwhile, General Sternwood is in search of his missing son-in-law, Rusty Regan. With each revelation, Marlowe grows increasingly convinced that the murder of Geiger is linked to Rusty's mysterious disappearance.
Marlowe's vigilant watch at the bookstore leads to another significant breakthrough when he observes the inventory being relocated to Brody's residence. Vivian Sternwood (played by Mary Beth Hughes) pays Marlowe a visit, laying bare the fact that Carmen is indeed being blackmailed with explicit photographs from the previous night. She confesses her own gambling troubles with Eddie Mars and reveals that Mona, Eddie's wife, had an affair with Rusty before disappearing with him.
As Marlowe continues to untangle the webs of deceit enveloping the case, he finds himself inexorably drawn into a vortex of trickery and treachery, with no clear path to resolution. A return to Geiger's estate reveals Carmen in a desperate search for evidence against her blackmailers. They jointly hunt for the crucial photographs, but Carmen is reluctant to divulge her involvement from the preceding evening. Just as Marlowe begins to pull the pieces together, Eddie Mars (played by John Ridgely) enters, masquerading as a concerned friend of Geiger. Despite Eddie's efforts to intimidate him, Marlowe remains unperturbed, assured in his power to thwart Eddie's dark schemes.
Upon arriving at Brody's place, Marlowe is faced with an unsettling scene: Brody affectionately snuggles with Agnes, the bookstore clerk. Marlowe quickly alerts Brody that he is aware of their plot to manipulate the lending library and blackmail Carmen. The tension escalates as Carmen bursts in, brandishing a gun and demanding the damaging evidence. However, Marlowe, quick on his feet, disarms her and firmly ejects her from the situation.
Undeterred by the dangerous implications, Marlowe dives deeper into the matter. He unravels the guilt-laden threads of blackmail involving Geiger, the unexplained motives of Owen Taylor for killing Geiger, and Brody’s pursuit of the family chauffeur, leading to the theft of the incriminating film. In a dramatic turn of events, Brody meets a fatal end at the hands of Carol Lundgren, Geiger's lover, who mistakes him for his slain partner.
As Marlowe's investigation progresses, he turns his focus to the inexplicable disappearances of Rusty and Mona. Authorities dismiss their vanishing as a spontaneous elopement, but Marlowe's instincts tell him a different story. Invited to Mars' casino, he finds himself in a tense discussion where Vivian's presence only exacerbates the precarious air between them.
While driving Vivian home, she tries to charm him with her flirtation, but the seasoned investigator is unfazed. Upon returning to his own quarters, he is taken aback to find Carmen in his bed, only to be rebuffed yet again. Even as the complex case seems to reach its conclusion, Marlowe is haunted by the feeling that many elements remain unresolved.
The following day, he is approached by Harry Jones, Agnes's new partner, who offers crucial information about Mona "Silver-Wig" Mars. However, Eddie’s henchman, Lash Canino, harbors suspicions and brutally disposes of Jones. Undeterred, Marlowe manages to connect with Agnes, extracting the vital information despite the looming threats. His journey leads him to a repair shop in Realito, where he attempts to confront Mona, only to find himself ambushed by Canino and his accomplice, Art Huck, the garage mechanic. Left for dead, Marlowe awakens to find himself tied up with Mona, who claims she hasn't seen Rusty for months and has merely been hiding to assist Eddie.
Later, Marlowe pays another visit to General Sternwood, who remains curious about Rusty's fate. In exchange for solving the mystery, Sternwood is willing to offer an additional reward. As Marlowe departs, he returns Carmen's gun, which leads her to seek his assistance in learning to properly handle it. They head to an isolated field where Carmen, eager to impress, tries to take aim at him, only for Marlowe to reveal he has filled the gun with blanks, leaving her astonished and confused. The shock triggers an epileptic episode, which Marlowe quickly alleviates, taking her to safety.
In the aftermath, Marlowe is finally able to piece together the chilling truth: Carmen's obsession with Rusty led to rejection, culminating in a tragic scenario of deception and ulterior motives. Eddie, who initially backed Geiger, played a crucial role in manipulating Vivian, fabricating a story about Rusty's departure alongside Carmen, subsequently leveraging it for blackmail. Vivian ultimately reveals that she took extreme measures to keep the truth hidden from her father, fearing his displeasure.
With the case drawing to a close, Marlowe finds solace in a local bar, drowning his thoughts in double Scotches while pondering the enigmatic Mona "Silver-Wig" Mars. Though their paths may never intersect again, the intrigue surrounding her character lingers in his mind, fostering a sense of existential disquiet.
