In this legendary Gershwin opera set among the black residents of a fishing village in 1912 South Carolina, Bess - a woman with a disreputable history - tries to break free from her brutish lover Crown after he becomes wanted for murder. The only person willing to overlook her past and offer her shelter is the crippled Porgy. Their relationship is threatened by the disapproval of the townspeople, the presence of her old drug supplier Sportin' Life - and the threatened return of Crown.

At Catfish Row, the courtyard home to a southern, African-American fishing community, the men shoot dice one evening while the women gossip about the wanton Bess, who for five years has lived with Crown, a local bully. The women declare that Porgy, a cripple who gets around on a cart pulled by a goat, is "soft on Bess," but Porgy denies this and laments that the life of a cripple is meant to be lonesome. When Crown and Bess come to the courtyard and Crown joins the dice game, Sportin' Life, a slick drug pusher, sells Crown some "happy dust," or cocaine, against Bess's wishes, and Crown snorts it. When Robbins, one of the dice players, wins his point, a fight ensues in which Crown kills Robbins with a blow. Bess sends Crown away to protect him from the police, then asks Sportin' Life for some happy dust. Sportin' Life suggests that they leave for New York together, but Bess turns him down in disgust. When the police arrive, Bess tries to take refuge with her neighbors, but they all turn her away. Desperate, Bess knocks at Porgy's door, he agrees to let her stay. Serena, the God-fearing woman who was married to Robbins, tries to collect money from the community to pay for her husband's burial, and although she refuses Bess's contribution, Porgy encourages the neighbors to be generous and Bess collects their offerings. When a white detective accuses old "honey man" Peter of the murder and threatens him, Peter reveals that he saw Crown kill Robbins. Peter is then locked up as a material witness until Crown is caught. The detective warns Serena that if Robbins is not buried by the next day, the board of health will turn his body over to medical students. After Serena pleads with the undertaker to accept the fifteen dollars she has collected and let her pay the rest when she earns it, and he agrees to bury the body. Bess continues to live with Porgy, and the neighbors soon notice that he is happier. One day, lawyer Frazier comes to give Bess a divorce from Crown so she can marry Porgy, for which Porgy pays him a dollar, but when Frazier learns that Bess never married Crown, he demands an extra half-dollar. When they balk, Frazier accuses them of living in sin, and Porgy reluctantly pays the amount. On the day of a church picnic, Sportin' Life again tempts Bess to go to New York and offers her happy dust, but Porgy threatens to break his neck unless he leaves Bess alone. Porgy then tells Bess that she is now his woman and she agrees to stay with him. After the picnic, Crown, who is hiding in the woods, confronts Bess when she is alone. She struggles to resist him, but when Crown kisses her, she embraces him and lets him carry her off. Bess returns to Catfish Row two days later and remains in a state of delirium for more than a week as Porgy tends to her. Peter, who has been released from jail, recommends that Porgy take Bess to the county hospital, but he refuses and instead asks Serena to pray for Bess. After reciting a prayer, Serena states that Bess will be well when the church bell strikes six times. The next morning, when the bell chimes, Bess comes out of her delirium and calls for Porgy. Realizing she betrayed him with Crown, Bess cries but Porgy forgives her. Although Bess confesses that she loses control when Crown touches her, she tells Porgy she loves him and asks him not to let Crown seduce her. He assures her that he will protect her from Crown and that she has a man now. When a hurricane hits after some of the men have gone out in their fishing boats, the people congregate at Serena's home, where Clara, a new mother, worries about her husband Jake. Crown also comes to the house where he taunts Porgy about his relationship with Bess, then laughs at those who are afraid of the storm. Anxious, Clara gives her baby to Bess and runs out in search of Jake, after which Crown also leaves, saying that he will be back for Bess. Following the storm, the community mourns for the lost men and Clara. When Serena tries to get Bess to give up Clara's baby, saying it needs a proper Christian raising, Porgy implores Serena to let Bess keep the child, and Serena relents. Later, Crown sneaks into the courtyard and goes to Porgy's window, and when Porgy awakens, they fight. When Crown draws his knife, Porgy throws him down, killing him. As the people repair their buildings from the storm damage, the detective returns with a coroner to find a witness to Crown's killing. Suspecting that Serena killed Crown for revenge, the detective questions her, but she has an alibi. The detective then orders Porgy to come to the jail to identify the body. Porgy refuses, not wanting to look at Crown, and Sportin' Life says that if Porgy looks at Crown's face, the dead man's wounds will begin to bleed, proving that Porgy killed him. The detective then carries Porgy into the police wagon as he screams that he will not look at Crown's face. Sportin' Life finds Bess crying and tells her that Porgy will "give himself away" and end up dying in jail. He offers her some happy dust, and after she accepts, Sportin' Life's talk of New York and living in a mansion appeals to her in her drugged state. Sometime later, the police bring Porgy back to the courtyard. He tells his friends that the wounds did not bleed when he looked at them and brings gifts he bought with money he won from shooting craps in jail. When he asks for Bess, however, the people scatter. He then sees Serena with Clara's baby and demands to know where Bess is. Porgy finally learns that Bess went to New York with Sportin' Life after he convinced her that Porgy would never return from jail. Stating that he cannot go on without Bess, Porgy starts off for New York in his goat cart, cheered on by his friends.