As soon as Thorwald is gone, Stella and Lisa run out of Jeff's apartment. Once he is alone, Jeff retrieves his flash from his camera bag. He watches Lisa and Stella sneak over the brick wall and start digging up Thorwald's flowerbed. Jeff calls Detective Doyle's house, but Doyle and his wife are out; he leaves a message with the babysitter. Upstairs, the songwriter has a group of lively guests over again. Through Miss Lonelyhearts' blinds, he can see that she hasn't actually taken the pills and is sitting at her desk writing something - meaning that Stella must have been wrong about her wanting to commit suicide.
Jeff focuses his camera lens back on Stella and Lisa. They show him that there is nothing buried in Mr. Thorwald's flowerbed. However, Mr. Thorwald is still out, so Lisa decides to climb the fire escape and sneak into his apartment. Jeff is clearly against this, but from his perch, there's nothing he can do to stop her. He can only watch as she goes into Mr. Thorwald's suitcase and removes Mrs. Thorwald's handbag - only to find that it is empty. She goes through his drawers. Stella bursts back into Jeff's apartment and tells Jeff to call Thorwald's apartment the second he sees Thorwald returning so that Lisa knows that it's time to get out.
Lisa continues searching through Thorwald's things. Suddenly, Stella shouts out, "Miss Lonelyhearts!" and tells Jefferies to call the police. He looks down to see that Miss Lonelyhearts is about to take a handful of the sleeping pills and dials the police department. However, before the pills reach her mouth, Miss Lonelyhearts stands up and goes to the window. Stella wonders if the music coming from the songwriter's apartment has stopped her from killing herself. At this moment, both Miss Lonelyhearts and Lisa are in the same position in the window, with Miss Lonelyhearts on the ground floor and Lisa above her in Thorwald's apartment. However, in the chaos over Miss Lonelyhearts, Jeff is late in signaling to Lisa that Thorwald is returning. Lisa hears Thorwald coming and has no choice but to hide instead the man's apartment.
Jeff is still on the line with the police department; a sergeant comes to the phone. Jeff reports a man assaulting a woman and gives the police Mr. Thorwald's address. Meanwhile, Thorwald re-enters his bedroom to find that the handbag he had packed in his suitcase is now sitting on the bed. He turns around and sees Lisa there. Even though her voice doesn't carry across the courtyard, it is clear that she's trying to explain what she's doing in Mr. Thorwald's apartment. He grabs her by the wrist and throws her down. Jeff is terrified. Lisa and Thorwald start to struggle, and Lisa screams Jeff's name. Thorwald turns off the lights in his apartment; Jeff is beside himself with fear.
The police come to Thorwald's door and he goes to answer it. Jeff focuses his lens on Thorwald's face as he tries to explain what's been happening. The police speak to Lisa and Thorwald; Lisa crosses her hands behind her back and indicates to Jeff that she is wearing Mrs. Thorwald's wedding ring. Thorwald sees her gesture at the same time as Jeff does and looks straight into the Jeff's lens/the camera. Jeff quickly commands Stella to turn off the light, but Thorwald has already seen them. In the dark, Jeff and Stella start collecting cash to bail Lisa out of jail. Stella goes to the police station, leaving Jeff alone.
Jeff's phone rings; it's Doyle. He starts to lecture Jeff about making up killer stories when Jeff hisses that Lisa has been arrested. He adds that Lisa has Mrs. Thorwald's wedding ring. He excitedly tells Doyle about all the conclusions he has drawn about Mr. Thorwald and continues to insist how certain he is that Mr. Thorwald has indeed killed his wife. Doyle asks where Lisa's being held; he says he will go down to the precinct and get her out of jail. After Jeff hangs up, the phone rings again. Jeff assumes it's Doyle and starts talking to him, but then realizes that it isn't. Whoever is on the other end hangs up the phone.
Jeff hears footsteps coming up the stairs towards his apartment and wheels himself to the door to wait. He has his flashbulb on his lap. The door opens and Mr. Thorwald enters Jeff's apartment, silhouetted against the light from the hallway. He asks Jeff, "What do you want from me?" Thorwald goes on to say that Lisa could have turned him in, but she didn't - why not? Thorwald then says he does not have a lot of money and keeps demanding that Jeff answer his questions. Thorwald asks for the wedding ring, but Jeff says that the police have it now.
Jeff sets off his flash and momentarily blinds Thorwald, who is quickly coming towards him. He flashes the killer again and again, slowing down Thorwald's approach. He looks across the courtyard and sees Lisa and Detective Doyle about to enter Thorwald's apartment; Jeff calls out their names just as Thorwald lunges forward to strangle him. They hear him and run outside. Thorwald grabs Jeff, throws him out of his wheelchair, and dangles him from the window. Everyone in the courtyard comes to their windows upon hearing the scuffle as Jeff struggles to hold onto the ledge.
The policemen grab Thorwald and rip him away from the window; Jeff loses his grip and falls to the ground. Lisa runs over and cradles Jeff's head in her hands. He tells her that he wouldn't have been able to forgive himself if anything happened to her, and that he's proud of her. Another policeman reports that Thorwald has confessed to murder; as Jeff suspected, he cut up Mrs. Thorwald's body and disposed of it in the East River. There was actually something buried in the flowerbed, but the dog got "too inquisitive", so he moved it to a hatbox in his apartment. Fade out.
It's daytime, and Miss Lonelyhearts is visiting with the songwriter, who offers to play her his new song. She is enchanted by his music. Across the courtyard, painters are covering the walls in the Thorwalds' now empty apartment. Above that, the woman on the fire escape is speaking sweetly to her new puppy. The camera wanders down to Miss Torso's apartment, just as she greets a short, squat soldier named Stanley with a romantic embrace. The woman with the hearing aid is passed out on her lawn chair; the newlyweds have started fighting. Inside Jeff's apartment, Jeff is asleep in his wheelchair, now with both legs in casts. Nearby, Lisa sits on the bed, dressed down in jeans and a shirt, reading a book called "Beyond the High Himalayas." Once she sees that Jeff is asleep, she puts down the book and picks up Harper's Bazaar.
Jeff thrives on constant action; the lack thereof makes him anxious. In the very beginning of the film, Jeff begs his editor to send him back out on assignment. When Stella warns him that his spying could land him in prison, Jeff tells her that he'd welcome the excitement. Over the course of the film, it becomes clear that one of the reasons that Jeff likes being in dangerous situations is to avoid his own personal dilemmas. In this final section of the film, Jeff learns that his constant need for stimulation can have deadly effects; he inadvertently ends up putting himself as well as Lisa and Miss Lonelyhearts in danger. Fully aware of Stella's warning that Miss Lonelyhearts might be preparing to commit suicide, Jeff still turns his camera away from her the minute she puts down the pills, jumping to the conclusion that Stella was wrong and retraining is camera on the faster-paced mystery upstairs. It is only when Stella returns to the apartment that she alerts Jeff to the fact that Miss Lonelyhearts is still in a dark place, even if the pills are no longer in her hand.
Hitchcock also creates a very deliberate visual (and thematic) parallel between Miss Lonelyhearts and Lisa. When the songwriter starts playing, Miss Lonelyhearts abandons her pills and stands at her window, listening. Right above her, Lisa is standing in the same position, holding Mrs. Thorwald's necklace and waving it at Jeff. Both women are enchanted by the romantic music because both of them want love. Miss Lonelyhearts has struck out so many times that she's ready to take her own life, while Lisa is risking hers in order to hold on to Jeff. Not only does this shot serve as proof of the detrimental effects of loneliness that Jeff refuses to accept, it is also the first time that Jeff is turning his camera on Lisa. From this distance, the similarities between Lisa and Miss Lonelyhearts send a blatant message; it's just a matter of Jeff understanding what it means.
While she can't seem to seduce Jeff with traditional romantic overtures, Lisa has his full attention when she's on the other side of his lens, and she takes full advantage of her position. This means that while Lisa is in Thorwald's apartment, she is not exactly careful. She keeps holding up various pieces of evidence to show Jeff, which slows down her sleuthing. Finally, when she slips on Mrs. Thorwald's wedding ring, she makes a poorly-concealed gesture to make sure Jeff sees it, which is ultimately what alerts Thorwald to Jeff's existence. Donald Spoto writes that Lisa's showing off the ring allows Hitchcock to "close the circle of his intention: Lisa has seen the entire adventure as a way of showing Jeff what a good wife she'd be; she slips on the ring not only to prove their suspicions about the fate of Mrs. Thorwald but also as a kind of proposal to Jeff." Even though Lisa's lack of slyness blows open their entire operation, Jeff is proud of her putting herself in danger, just like he did when he was taking photos of the racetrack accident that left him injured. This further proves Jeff's addiction to thrills and his subsequent lack of neighborly compassion.
In Jeff's final confrontation with Thorwald, however, Jeff (and the viewer) finally has to face what's right in front of him. Without his camera, Jeff can no longer distance himself from danger. In the tense moments before Thorwald arrives at Jeff's door, the camera moves in slowly on Jeff's face; it is as if he is now the one being watched. The tables have turned and Jeff is the vulnerable one, emphasized by the high-angle close-up that Hitchcock employs as Jeff turns his wheelchair around to face his front door. Then, when Thorwald comes inside, he asks Jeff what he wants, but Jeff doesn't say anything - because he doesn't have an answer. From the beginning of the film, Jeff has only ever been interested in Thorwald out of curiosity and a lack of other distractions.
When Thorwald is inside his apartment, Jeff does not physically defend himself. He uses his flashbulb to delay Thorwald's approach, but he does not actually attack. Roger Ebert writes, "There are crucial moments in the film where [Jeff] is clearly required to act, and he delays, not because he doesn't care what happens, but because he forgets he can be an active player; he is absorbed in a passive role. Significantly, at the end, when he is in danger in his own apartment, his weapon is his camera's flashgun; he hopes to blind or dazzle his enemy, and as the man's eyesight gradually returns, it is through a blood-red dissolve that suggests passion expressed through the eyes." As Thorwald gets closer to Jeff, the camera returns to its subjective angle; the viewer is once again aligned with Jeff. When Thorwald's hands come towards Jeff's neck, they are coming towards camera as well. We feel Jeff's fear, and this is Hitchcock reminding us that voyeurism is never without consequences.
Hitchcock ties up the loose ends of the Thorwald murder fairly quickly - we never see Thorwald confess, and the camera ambles by the now-empty Thorwald apartment during the epilogue to show that the salesman is no longer there. The reason for this is that the Thorwald murder is not the central conflict of Rear Window. Donald Spoto writes, "Hitchcock is frankly unconcerned with the killer and his wife... we don't see the actual crime...we know nothing about this man and woman, nor about their histories, their life together or the nature of her 'illness.'" The true climax of the film is when Lisa rushes to Jeff's side and he tells her that he's proud of her. She has inspired him to realize how much he cares about her. However, the ending of the film in which Jeff has two broken legs does contain a final visual message. Spoto claims that Jeff's fall is "a kind of retribution... he will have to relive the enclosed situation, but with Lisa instead of Stella as his companion, and with his wheelchair significantly facing away from the rear window."