Marlowe is a 33-year-old private investigator operating in 1930s Los Angeles. Formerly an investigator for the local district attorney before being fired for insubordination, he now works independently, charging twenty-five dollars a day plus expenses. He maintains a tough, cynical exterior but operates by a strict personal code of ethics and fairness. His independent mindset frequently puts him at odds with wealthy clients and corrupt local authorities alike.

The aging patriarch of the Sternwood family is a wealthy former oil magnate whose failing health confines him to a wheelchair. He harbors deep affection for his missing son-in-law, Rusty Regan. The general hires Marlowe to handle a blackmailer who holds promissory notes from his youngest daughter, seeking to resolve the issue quietly. He possesses a pragmatic worldview shaped by his accumulated wealth and past experiences.

The older Sternwood daughter is a sophisticated woman who shares her father's striking black eyes and strong will. Married three times, her current husband, former bootlegger Rusty Regan, recently disappeared without explanation. She frequents Eddie Mars's casino and gambles heavily. She attempts to manage Marlowe's investigation to ensure it aligns with her own efforts to shield her family from public scrutiny.

General Sternwood's younger daughter is an erratic young woman whose impulsive behavior frequently endangers the family's reputation. She owes massive gambling debts to Arthur Geiger, prompting the initial blackmail scheme. She exhibits little sense of social boundaries and frequently forces herself into compromising situations. Her reckless actions serve as the catalyst for Marlowe's involvement in the Los Angeles underworld.

Geiger is a plump, middle-aged man who operates a supposedly respectable bookstore in Hollywood. The business actually serves as a front for renting illegal pornography to wealthy clientele. He leverages the secrets of his prominent customers to run a lucrative blackmail operation. His aggressive extortion of Carmen Sternwood sets the primary plot in motion.

Mars is a sophisticated crime boss who operates the Cypress Club, a high-end coastal casino. He wears well-tailored gray suits that match his graying hair and cool personality. He commands a network of illegal enterprises and employs various thugs to enforce his will. He views Marlowe with a mixture of annoyance and calculated caution as the detective's inquiries threaten his operations.

Regan is Vivian's missing husband and a former commander in the Irish revolution. A former bootlegger with a background in organized crime, he possesses a rugged charm that endeared him to General Sternwood. His sudden, unexplained disappearance casts a long shadow over the Sternwood family. He is known for moving quickly and playing for high stakes.

Ohls is the chief investigator for the Los Angeles District Attorney. A medium-sized man with stiff white eyebrows, he is a practical and efficient law enforcement officer. He previously worked alongside Marlowe and maintains a professional respect for the private investigator. Ohls serves as Marlowe's primary connection to official police matters, though he must function within the systemic corruption of his department.

Norris is the Sternwood family's butler. He is a tall, silver-haired man in his sixties with an exceptionally composed presence. He manages the day-to-day operations of the sprawling estate and acts as a discreet buffer between the family and the outside world. He understands the complex dynamics of his employers and quietly facilitates Marlowe's investigation when it aligns with the general's interests.

Brody is an opportunistic criminal and former lover of Carmen Sternwood. Having previously extorted General Sternwood to stay away from Carmen, he routinely seeks new avenues for profit. He attempts to leverage illicit materials to extract money from the family. He possesses more ambition than actual criminal cunning, putting him entirely out of his depth.

Lundgren is a young, handsome man who works as a valet at Geiger's bookstore. He lives with Geiger and is fiercely devoted to him. He has a lengthy criminal record and reacts to stressful situations with immediate physical aggression. His deep emotional attachment to his partner drives his volatile actions.

Canino is a brutal hitman frequently retained by Eddie Mars. He is a short, heavily built man who consistently wears brown clothing and drives a brown car. He executes his assignments with casual cruelty and zero hesitation. He represents the violent, unvarnished reality of the Los Angeles criminal underworld that Mars attempts to gloss over.

Born Mona Grant, she is a former cabaret singer married to casino owner Eddie Mars. She disappeared from Los Angeles around the same time as Rusty Regan, sparking rumors of a scandalous elopement. She wears a platinum wig over closely cropped hair to disguise her identity. Despite her husband's criminal nature, she remains staunchly devoted to him.

Taylor is the young chauffeur employed by the Sternwood family. He possesses a minor criminal record and harbors deep, unrequited feelings for Carmen Sternwood. The family previously intervened to quash legal charges against him. His emotional attachment to his employer's daughter severely compromises his judgment.

Agnes is an attractive, cynical woman who manages the public-facing operations of Geiger's illicit enterprise. She is acutely aware of the criminal nature of her workplace but remains focused on her own survival and financial gain. She frequently aligns herself with small-time operators in attempts to secure a larger payout. She views the men in her life with weary disappointment.

Jones is a small, careworn man in a tweed overcoat who previously smuggled liquor during Prohibition. He operates on the fringes of the Los Angeles underworld, picking up scraps of information to sell. He associates with Agnes Lozelle and attempts to leverage his knowledge about Rusty Regan's disappearance into a payout. He is physically unimposing but displays surprising courage.

Wilde is the portly District Attorney for Los Angeles. He previously fired Marlowe for insubordination but recognizes the private investigator's effectiveness. He struggles to balance his duty to uphold the law with the political realities of protecting wealthy citizens from scandal. He operates comfortably within the gray areas of municipal justice.

Cronjager is a police captain whose precinct covers the locations of several recent crimes. He is a hatchet-faced man with nervous fingers who resents private investigators operating on his turf. He represents the established law enforcement bureaucracy that Marlowe frequently circumvents. He prioritizes closing cases quickly over unraveling complex truths.