Short Summary:
The play takes place right after World War II, in New Orleans.
The Kowalski apartment is in a poor but charming neighborhood in the French Quarter. Stella, twenty-five years old and pregnant, lives with her blue collar husband Stanley Kowalski. It is summertime, and the heat is oppressive. Blanche Dubois, Stella's older sister, arrives unexpectedly, carrying all that she owns. Blanch and Stella have a warm reunion, but Blanch has some bad news: Belle Reve, the family mansion, has been lost. Blanche stayed behind to care for their dying family while Stella left to make a new life for herself, and Blanche is resentful. Blanche meets Stanley for the first time, and immediately she feels uncomfortable. We learn that Blanche was once married, when she was very young, but the boy died.

The situation grows more and more tense. Stanley initially distrusts Blanche, thinking that she's swindled them; the idea is ludicrous, and eventually Stanley realizes that Blanche is hardly the swindling type. But the animosity between the two never stops. Blanche takes long baths, criticizes the squalor of the apartment, and irritates Stanley. Stanley's roughness bothers Blanche; he makes no effort to be gentle with her. One night, the night when Stanley hosts a poker game, he gets too drunk and beats Stella. The women go up to their upstairs neighbors' apartment, but soon Stella returns to Stanley, the two coupling with an animal-like need. Blanche is shocked by these events. That night, she also meets Mitch, and there is an immediate mutual attraction between the two.

The next day, Stanley overhears Blanche saying terrible things about him. From that time on, he devotes himself fully to her destruction. Blanche has a shady past in Laurel. In her loneliness, during the last days of Belle Reve and after the mansion was lost, she turned to strangers for comfort. Her numerous amorous encounters destroyed her reputation in Laurel, leading to her loss of her job as a high school English teacher and her near-expulsion from town.
Tensions build in the apartment throughout the summer. Blanche and Stanley look on each other as mortal enemies, and Blanche turns increasingly to alcohol for comfort. Stanley bides his time.

Stanley looks into Blanche's past, and he passes the information on to Mitch. Although previously it seemed that Blanche might marry Mitch, after he learns the truth he loses all interest. In autumn, on Blanche's birthday, Mitch stands her up. Stanley presents Blanche with her gift: bus tickets back to Laurel. Blanche is overcome by sickness; she cannot return to Laurel, and Stanley knows it. As Blanche is ill in the bathroom, Stella fights with Stanley over the cruelty of his act. Mid-fight, she tells him to take her to the hospital: the baby is coming.
That night, Blanche packs and drinks. Mitch arrives. He confronts her with the stories of her past, and she tells him, in lurid detail, the truth about her escapades in Laurel. He approaches her, making advances, wanting what she has denied him all summer. She asks him to marry her, and when he doesn't, she kicks him out of the apartment.

Hours later, Stanley comes home. Stella is still in labor, and will be until morning, so Stanley's getting some sleep. Stanley mercilessly destroys Blanche's illusions, one by one, and then rapes her.
Weeks later, another poker game is being held at the Kowalski apartment. Blanche has suffered a mental breakdown. She has told Stella what Stanley did, but Stella has convinced herself that it can't be true. A doctor and nurse come and take Blanche away to the asylum. Stella weeps, and Stanley comforts her. The other men continue their poker game as if nothing has happened.