L.B. Jeffries (James Stewart), a photojournalist for a big time magazine is confined to his Greenwich Village apartment in a leg cast due to an accident during a photo shoot when he got a little too close to the action on a race track. His long period of convalescence is stifling. Use to being on the move, traveling to exotic places around the world, Jeffries is bored and frustrated by his inability to get around. A brutal heat wave with temperatures hovering around 100 degrees only adds to his aggravation. Bored out of his mind, Jeffries spends his days and nights, voyeuristically spying on his neighbors whose apartments are visible from his window facing the courtyard of his housing complex. The tenants are a diverse group of New Yorkers whose lives he becomes fleetingly acquainted with. They include a newlywed couple, a struggling songwriter, a lonely woman, he dubbed Miss Lonely Heart, a young beautiful dancer he nicknamed Miss Torso, and some married couples, one with a dog, another who sleep out on the fire escape, and especially one unhappy couple, Lars Thorwald (Raymond Burr) and his ailing wife.
Jeffries girlfriend, Lisa Freemont (Grace Kelly), a high fashion model, is pushing him to settle down and get married, a concept Jeffries reacts to as if it were allergenic. Jeffries begins to focus on the Thorwald’s when he notices Mrs. Thorwald, who was always in her bedroom, has seemed to have disappeared and Mr. Thorwald, a salesman by trade, began to be going out at odd hours of the night with his sample case in hand.