L.B. "Jeff" Jeffries, portrayed by James Stewart, finds himself recuperating from a fractured leg during a sweltering summer in New York City. Once a dynamic and successful photographer, renowned for capturing elusive moments, Jeff's life changes dramatically after an accident involving a racing car that not only destroys his camera but also leaves him confined to a wheelchair. Living in a modest apartment, Jeff now spends his recovery watching the lives of his neighbors unfold through the rear window, observing their everyday routines with an almost voyeuristic curiosity.
This peculiar pastime becomes his main occupation, as he takes in the sights of a diverse cast of characters, including a woman who exercises in her underwear, a couple seeking relief from the heat by sleeping on their balcony, a struggling songwriter diligently working at his piano, and a troubled salesman, who frequently argues with his bedridden wife.
Their lives provide Jeff with a window into the mundane and the perplexing, but it isn't long before he feels the weight of his own stagnation. His therapist, Stella, visits regularly, imparting wisdom while chiding him for his idle habits, sensing trouble brewing as he fixates on his neighbors' dramas. Stella suggests he should redirect his thoughts towards his lovely girlfriend, Lisa Carol Fremont, a wealthy and successful socialite. Jeff, however, feels unworthy of her affections, believing that their starkly different lifestyles could never harmonize. With a sigh, he admits, "Sure, she's a wonderful girl, but she's also a rich, successful socialite," and he fears he can't provide her the stability she deserves.
Just as Stella departs, Lisa arrives, resplendently dressed, embodying the image of the glamorous socialite, and clearly smitten with Jeff. Their dinner conversation soon turns to the future, intensifying their differing perspectives, and culminating in a heartfelt argument. Lisa bids him farewell, leaving Jeff with a heavy heart and lingering doubts about their relationship.
As the night drags on, Jeff is restless in the sweltering heat and drifts into a fitful sleep. He awakens to a curious sight across the courtyard—a neighbor, the salesman, carrying a heavy silver briefcase at the odd hour of 1:55 AM. The shadows cast by the drawn blinds keep Jeff from glimpsing the man's wife, whose absence quickly begins to arouse his suspicion. When the salesman returns at 2:35 AM appearing unusually light, Jeff's intrigue deepens.
Daybreak brings a renewed interest in the happenings next door, especially when Jeff and his companions notice that Mrs. Thorwald seems to have mysteriously vanished. The dynamic trio of Jeff, Lisa, and Stella gathers evidence about Lars Thorwald, played by Raymond Burr, leading them to conjecture about foul play. They shake off their initial doubts when an old friend, Thomas J. Doyle, a police detective, insists there’s no cause for alarm, but as they investigate further, they can’t help but obsess over the unsettling clues.
A chill ripples through the humid air when a small dog from the courtyard turns up dead, its body found in the Thorwald's flower bed, underlining the sinister atmosphere. As Jeff’s suspicions intensify, he notes discrepancies in the garden's appearance—specifically, a recently disturbed zinnia plant. This leads to an urgent inquiry; he and Lisa craft a note addressed to Thorwald, questioning "What have you done with her?" and anxiously await his reaction.
As Lisa embarks on a daring mission to uncover more secrets within Thorwald's apartment, Jeff's frustration and fear grow. Her discoveries—a purse and wedding ring belonging to the missing Mrs. Thorwald—confirm his most dreadful suspicions. Tension mounts as Thorwald returns unexpectedly, and Lisa, trapped, finds herself in imminent danger.
The scene becomes a pulse-pounding race against time as Jeff and Stella watch helplessly from their own apartment, desperately trying to reach the authorities as they witness Lisa's plight. The drama escalates further, leading to a climactic confrontation that leaves Jeff battling for his life against the ruthless salesman who has been living a double life.
After a harrowing struggle, the police intervened just in time to rescue Lisa and apprehend Thorwald, who confesses to his wife's murder.
As the oppressive heat lifts in New York, the camera pans through the neighborhood, showcasing the aftermath of the turmoil. Jeff, now with two broken legs from the fall during the struggle, finds comfort in the presence of Lisa, who nestles next to him, deeply in love yet now sporting a casual attire reminiscent of the adventurous life Jeff had once sought. However, even as she expresses her affection, she conceals a fashion magazine, hinting at a duality in their lives that suggests more surprises are yet to come.
