Jim and Irene Westcott live contentedly on the 12th floor in an apartment building with their two children near Sutton Place (their city of residence is not mentioned, but Sutton Place is in New York City). Both Jim and Irene enjoy music very much, regularly attending concerts and spending a lot of time listening to music on their radio. However, the Westcotts keep their interest in music from their friends.
When their old radio breaks down, Jim orders a new one, but when it arrives Irene is shocked at the complete and utter ugliness of the device that Jim has bought. The radio is described as a large gumwood cabinet with numerous dials and switches that light up with a green light when it is plugged in. Until the new radio arrived, the Westcotts hardly ever argued and seemed to have a happy marriage.
One night, as Irene is sitting in the apartment listening to the radio she starts to hear interference in the form of a rustling noise over the music concert that is being broadcast. She tries to get the music back by flipping all of the switches and dials, but then begins to hear the sounds of people from other apartments in the building. She is so surprised by this that she shuts off the radio. Later that evening when Jim arrives home from work, he tries the radio to get some music. Instead of music, Jim hears elevator noises and doorbells.Believing that the electronics in the building are interfering with the signal he decides to turn off the radio and call the people who sold it to him and demand to have the radio repaired.
The radio is examined and the problem apparently fixed, but the next day while Irene is listening to a Chopin prelude she hears a man and woman who seem to be arguing. Realizing that the conversation is coming from people who live in a nearby apartment, she flicks a switch, but next hears a woman's voice reading a children's story, which she recognizes as belonging to her neighbor's children's nanny. She flips the switch again, but each time she does so she becomes privy to the events in another apartment. Irene demands that Jim turn off the radio because she is afraid her neighbors will hear her and Jim, just as they can hear the others in the building.
Over the next few days Irene listens in on the lives of her neighbors, and finds herself becoming both intrigued and horrified. Irene becomes so obsessed with listening in on her neighbors, that she cuts a luncheon short with a friend to go home and listen to the radio to hear what news would be revealed next in the lives of friends and neighbors. Jim notices how strange Irene has become in her ways and conversations, especially at a dinner party the Wescott's attended. On the way home, Irene speaks of the stars like a little candle throwing its beam as to "shine a good deed in a naughty world."
Irene becomes totally involved in the lives on the radio and becomes depressed herself. She has gone from a pleasant, rather plain woman, to a woman who doubts who she is and doubts her relationship with her husband Jim. Once more, Jim arranges for the radio to be examined and this time the repairs are successful. The repairs are expensive and a great deal more than Jim can afford. All he wanted was for Irene to get some enjoyment from the radio. Instead the radio brings the Westcotts' peaceful life to an end. Not only is the second repair of the radio more than Jim could afford, but he also finds unpaid clothing bills on Irene's dressing table. Thus the beginning of the hidden truths coming to the surface; Jim worrying about money issues and Irene worrying about the radio hearing their argument and the past indiscretions of her life.