Directed by Alfred Hitchcock, a recuperating photographer spies on his neighbors and suspects that one of them has murdered his wife. He persuades his girlfriend and nurse to help him try to crack the case that his detective friend makes fun of.
Photographer L. B. Jeffries is laid up with his broken leg in a cast, and his boss calls. Jeff says he can’t do anything for the next six weeks but look out his window. He sees Lars Thorwald (Raymond Burr) working on his roses being belligerent to a neighbor. His nurse Stella (Thelma Ritter) comes in and calls him a “peeping Tom.” He says there will be trouble, and she gives him a massage. He says he is not ready to marry Lisa because she is too perfect. Stella says psychoanalysis has complicated life too much. Jeff observes a newly wed couple cross the threshold.
In the evening Lisa Carol Fremont (Grace Kelly) wakes Jeff with a kiss and turns on the lamps. He notices her new dress. A waiter from 21 brings in dinner with wine. Lisa would like him to open a studio and stay home. He watches a woman pretending she has a guest for dinner who cries. Jeff says Lisa is like the ballet dancer who has three male visitors. He watches Thorwald’s wife laugh at Lars. After dinner Lisa and Jeff argue about his traveling, and he says she would not like its hardships. He doubts either one would change. She says goodbye but that she will come back tomorrow night.
Jeff is awakened at 1:55 a.m. by thunder. He sees Lars leave with a suitcase and come back forty minutes later and then leave again. Later the dancer comes home, and Lars returns with the suitcase. Jeff nods off.
The next day Stella massages Jeff’s back. Jeff says the salesman went out several times with his sales case. He sees Lars looking out his window at a dog in his rose garden. Before she leaves, Stella hands Jeff the binoculars. He spies on Lars. Jeff puts a telephoto lens on his camera. He sees Lars wrap a saw and a large knife in newspaper.
That evening Jeff and Lisa are kissing. He asks her why a man would leave his apartment three times with a suitcase in one night. Jeff believes something is terribly wrong. He asks how would one begin to cut up a human body. Lisa tells him to stop using binoculars. He asks why the invalid wife has not been seen all day. They see Lars with a trunk, and she asks Jeff to tell her the whole story. Lisa reports to Jeff by phone on her investigation.
Jeff calls his army friend, detective Lt. Doyle, about the suspected murder. Stella says she would cut up the body in the bath tub. Lars has two workers remove the trunk, and Stella goes out to see the trunk.
Lt. Thomas J. Doyle (Wendell Corey) doubts there was a murder but says he will investigate on his own without reporting it. Lars stops the dog from digging in his rose garden. Doyle tells Jeff that the Thorwalds left their apartment at 6 a.m. The superintendent said that Lars told him that his wife took a train. Jeff asks Doyle to search the Thorwald apartment, but Doyle says he must have a search warrant. Jeff tells him to find the trunk because Mrs. Thorwald is in it. Doyle says she sent a message that she arrived.
At night Jeff sees the dog being lowered in a basket. He spies on the lonely woman, who takes a drink and goes out. The dancer rehearses. Jeff sees Lars coming home with a box of laundry, and he begins to pack his clothes. Jeff calls and asks Mrs. Doyle to send her husband because Thorwald is packing. Lars calls long distance and takes jewelry from a purse. Lisa comes in, and Jeff says Thorwald is pulling out. Thorwald goes out, but Jeff says his things are still there. Lisa asks why a woman would go away and leave her jewelry in a handbag. Lisa suspects the witnesses saw another woman. They kiss, and Lisa says she is staying the night. She hears a song and sees a party. While she is changing, Doyle comes in. She brings them warm brandy and says she thinks Thorwald is guilty. Doyle gets a call and is still skeptical. He says the trunk had Mrs. Thorwald’s clothes. Doyle says the police reported that Mrs. Thorwald picked up the trunk, and he leaves.
The lonely woman brings home a young man. He tries to kiss her, and she hits him and makes him leave. Jeff asks if it is ethical to spy on people. Lisa closes their blinds and puts on a nightgown. They hear a woman scream, and they see that her dog is dead by the roses. The lonely woman says it was strangled and puts it in the basket. Jeff suspects Thorwald did it. Stella, Lisa, and Jeff watch Lars cleaning his apartment. Jeff looks at his photos and notices a change in the flower garden where the dog was digging. Jeff writes a note to Lars, asking what he did with her body. Lisa puts the envelope under his door. Jeff observes him as he reads it. Stella notices the lonely woman has sleeping pills. Lisa comes back and sees Lars with the handbag. Stella and Lisa want to dig in the garden, but Jeff cautions them. Jeff calls Lars and asks if he got his note. He proposes a meeting in the Albert Hotel bar to settle the estate of his late wife. He threatens to call the police if he does not come. Jeff sends the women out to dig and says he will signal with a flash bulb. Jeff calls Doyle and leaves a message with a servant. Stella digs but finds nothing. Lisa climbs the ladder and goes in the window of Thorwald’s apartment. She looks in the handbag and shows that it is empty. Stella has Jeff call the police. Lars comes home, and Jeff tells the police a man is assaulting a woman. They see Lisa talking to Lars, who grabs her. She calls to Jeff, and the police arrive. Lars lets them in, and he sees Lisa signaling to Jeff. He sends Stella to bail Lisa out of jail. Jeff calls Doyle and says Lisa was arrested. Jeff says Lisa got Mrs. Thorwald’s wedding ring as evidence. The phone rings, and Jeff realizes it is not Doyle. Jeff gets flash bulbs in the dark. Lars comes in and asks what he wants. Lars asks for the ring back. Jeff uses the flash bulbs to blind Lars, who tries to strangle him. Jeff calls to Lisa and Doyle. Lars tries to push him out the window. Jeff falls. A policeman tells Doyle that Lars is confessing that he dug up the body because of the dog.
In the final scene Jeff has both legs in casts, and Lisa reads a glamour magazine.
In this mystery the audience gets to watch a voyeur discover and solve a murder case with help from his friends. They are in danger while the audience is able to watch from a safe distance. This drama reflects how people in an urban culture have many neighbors in such close proximity that they may see and wonder about their private lives.