Catfish Row, in Charleston, South Carolina, is home to a Black community. One night in the courtyard, Clara is singing a lullaby to her little baby. Her husband, Jake, and the drug dealer, Sporting Life, are playing craps with some other men. They are joined by Robbins, whose woman, Serena, is reluctant to let him play. Clara's little baby still hasn't fallen asleep. Jake takes hold of the little one – he'll show everyone how to put a child to sleep! To the great amusement of the others, however, the baby just cries after he finishes his song. Peter the honey-seller arrives home with the crippled beggar Porgy. The men sit him down close to them. Soon the drunk and big-mouthed Crown arrives. At his side is his woman, Bess, with whom Porgy is supposedly smitten. The women, Serena and Maria, look accusingly at Bess, who takes great swigs from the whiskey bottle. The men grow absorbed in their dice game. Crown, meanwhile, continues to drink and snort from Sporting Life's “happy dust” as he grows increasingly aggressive. The game ends with Robbins as the lucky winner, sending Crown into a blind rage. Too powerful to be restrained by the other men, Crown attacks the victorious Robbins, eventually stabbing him to death. The company immediately scatters, as Bess attempts to return the completely inebriated Crown to his senses so that he'll run away before the police arrive. There's no need to worry about her, though: Bess always finds somebody to take care of her... After Crown clears off, Sporting Life wastes no time making his move on the woman: he wants to entice her to go to New York with him. Bess asks him for happy dust and sends him away. She then tries to find somebody who will take her in. Eventually, she is admitted by Porgy.
The next day, the community is mourning beside the corpse, as Serena collects money for the funeral. Porgy and Bess enter. At first, Serena rejects Bess's donation, but the girl informs her that she no longer gets her money from Crown. Now it comes from Porgy. Serena then accepts it. The detective enters with the policeman, and presently their suspicion falls on Peter, who tells them that he saw Crown kill Robbins. They take Peter in as a “material witness”. After the police depart, the undertaker appears. Even though Serena hasn't managed to collect enough money, he eventually agrees to bury Robbins. The mourners sing a spiritual, with Bess in the lead.
Early one morning around a month later, Jake and his fellow fisherman are getting ready to sail out the next day. Clara fears for the boys out on the sea, but Jake works hard to provide their young son with the brightest possible future. Porgy just smiles: all he needs are to have God and his woman with him. Serena and Maria agree that Porgy has been utterly thriving ever since Bess has been living with him. Sporting Life is again prowling the area, trying to sell “happy dust”, but Maria chases him away.
The “attorney” Frazier finds Porgy and informs him that in order for Bess to live with Porgy legally, she has to first divorce Crown. Even though Bess and Crown were not even married, Porgy pays Frazier the dollar and a half for the divorce.
A white gentleman, Mr. Archdale, arrives and inquires about Porgy. The members of the community are reluctant to answer him until it turns out that he has brought good news: he knows Peter from long ago and has paid his bond.
Left alone again, Bess is once more approached by Sporting Life, who chatters to her about life in New York and offers her drugs. Bess rejects both, but Sporting Life won't give up, until Porgy eventually chases him off. Porgy and Bess profess their love for each other.
As they get ready for a picnic on Kittiwah Island, the others urge Bess to come with them. Bess doesn't want to leave Porgy by himself, but he convinces her to go ahead and have fun without him.
On Kittiwah Island, the party is underway: Sporting Life leads most of the company in unbridled fun. Serena scolds them, and then warns them that it's time to go: the boat is about to depart.
Bess is about to follow the others when somebody whistles from the bushes. It's Crown. Bess tries to avoid him, but it's no use. In the end, she is unable to resist him.
A week later, Jake and the other fishermen leave Catfish Row for the port. Peter arrives home, free on bail.
In Porgy's room, Bess has been lying ill and delirious with fever ever since she returned home from the island. Serena says a prayer for Bess and promises Porgy that the sick woman will be back in good health by the afternoon. The singing of the strawberry woman and the crab man is heard.
Bess comes to. Porgy calmly tells her that he knows she was with Crown on the island, and it is up to her alone whether she wants to stay with him or go with Crown. She sincerely asks Porgy not to let Crown take her away. He promises to look out for her. Clara anxiously retruns from the shore: she's never seen the water looking so black. Maria attempts to calm her, but soon the hurricane bell is heard tolling.
The inhabitants of Catfish Row are praying to be spared from danger. Just as it occurs to Bess that Crown is certain not to survive such a huge gale on the island, there comes a knocking on the door. In comes Crown, there for Bess. She informs him that she is Porgy's woman now, but Crown just laughs. Then Clara screams by the window: Jake's ship has capsized. She hands her baby to Bess and rushes to the shore. Bess is worried that she went outside in the storm all alone, and asks one of the men to head after her. Only Crown ventures out into the raging gale. The others continue to pray.
The community mourns Clara, Jake and Crown, all lost in the gale. Bess sings a lullaby to Clara's little baby. The space empties out. Then Crown steals in through the gate and sneaks toward Porgy's door. Porgy, however, notices Crown in time and stabs him dead.
The next day, the detective visits Catfish Row again, this time with the coroner. They want to bring Porgy in to identify Crown's corpse. Porgy is terrified at the thought of having to see Crown's face again and tries to do everything to avoid the duty. Eventually, however, the policemen take him away.
Sporting Life alarms Bess by telling her that Porgy will spend his life behind bars. He again entices her with tales of New York life and happy dust. Bess resists him, but the dealer leaves a dose of the drug for her.
A week later, Porgy is allowed home and happily tells the inhabitants how he got rich playing craps in prison; he has even brought gifts. There's one person, however, whom he doesn't see. After everyone dodges his questions, Serena and Maria finally tell him the truth: Bess believed Sporting Life's story and went with him to New York. Full of resolve, Porgy gets underway to find his beloved.