Mario Bellini and his parents, Mama and Papa Bellini, own a newsstand in the Times Square subway station in New York City. One day, Mario hears a sound that is quite strange for New York: a cricket chirping. He tracks it down a finds a cricket in a pile of newspapers. Mario immediately cleans it off and makes it a bed out of a matchbox, then begs his parents to let him keep it as a pet. Mama grudgingly agrees, as long as he keeps it in the newsstand rather than taking it home.
That night the cricket, named Chester, meets two other animals that live near the newsstand in the station—a miserly mouse named Tucker and his best friend, Harry Cat. Chester explains to them how a cricket came to be in Times Square: he is originally from Connecticut, but got stuck in a human's picnic basket and taken on a train to New York City, where he was finally able to make his escape from the basket.
The other animals are immediately taken with the beautiful, musical sound of Chester's chirp. They offer to take him to Grand Central Station and put him on a train back to Connecticut, but suggest that he spend some time in the city to see if he likes it. Chester agrees, but feels very out of place.
The Bellinis' customer, a music teacher named Mr. Smedley, is also impressed with Chester's chirp when he hears it, and predicts that great things are in store for this cricket. Mario wants to find Chester a cricket cage to live in, so he takes Chester down to Chinatown to a store owned by a Chinese man named Sai Fong. Sai Fong is excited to see the cricket, and sells Mario an elaborate cage to keep him in for very cheap. Before leaving Chinatown, Mario has a fortune cookie. His fortune tells him that good luck is on his way.
Chester appreciates Mario's gesture but does not like the feeling of being locked in the cage, so he lets Tucker sleep in it instead, with some dollar bills from the newsstand's cash register to use as a bed. As Chester falls asleep in his cozy matchbox, he thinks about how he is actually beginning to like New York.
In the morning, however, he wakes up to find that he has eaten half of a two-dollar bill while dreaming that it was a leaf. Chester is distraught—Tucker suggests they frame someone, but Chester does not want to create any bad feelings between the Bellinis. As they discuss what to do, though, Mama Bellini comes to open the newsstand for the morning and sees what Chester has done. She is livid, and tells Mario that the only way Chester can stay is if Mario replaces the money somehow.
Mario is determined, and decides to work extra so that he can replace the two dollars. To bail Mario out, though, Tucker reluctantly gives Chester two dollars of his life savings, a pile of coins he has collected over the years, and they leave it on the newsstand for the Bellinis to find. Mama Bellini is true to her word, even though she does not know where the money came from, and lets Chester stay.
Mario thinks something is wrong with Chester's diet, and takes Chester down to Chinatown again to find out from Sai Fong what he should be eating. Sai Fong has another old Chinese friend over, and treats them to a full Chinese meal before giving Mario some mulberry leaves to feed to Chester.
Time passes, and eventually it has been two months since Chester came to New York. The animals celebrate with a party, but while dancing, Tucker knocks over some matches and sets the newsstand on fire. Only some magazines burn, but Mama has had it with the cricket, and demands that they get rid of him immediately.
Before they do, though, Chester begins to chirp, and Mama is caught off guard by the beauty of it. Catching on, Tucker encourages Chester to chirp more music, and he begins to chirp Mama's favorite song. She is so taken with him that she agrees to let him stay.
This is the start of something huge for Chester Cricket. He listens to the radio every night to learn new music, and the Bellinis hold concerts twice daily for people to come hear the talented musical cricket. This eventually grows to be too much for Chester, though. He is not used to playing so frequently, and wishes he could go back to composing his own music at his leisure. He is not happy in New York anymore, and after a week of concerts, he decides the time has come to return to Connecticut.
The animals are sad to see him go, but escort him to Grand Central Station after he plays his final concert. When Mario sees that Chester has vanished, he knows he will not come back, and is glad because it means Chester will be happier. The book finishes off with Tucker and Harry mulling over the idea of taking a trip to Connecticut the following summer.