After the loss of her family home to creditors, Blanche DuBois travels from Laurel, Mississippi, to the New Orleans French Quarter to live with her younger married sister, Stella, and Stella's husband, Stanley Kowalski. She is in her thirties and, with no money, has nowhere else to go.
Blanche tells Stella that she has taken a leave of absence from her English-teaching position because of her nerves (which is later revealed to be a lie). Blanche laments the shabbiness of her sister's two-room flat. She finds Stanley loud and rough, eventually referring to him as "common". Stanley, in return, is suspicious of Blanche, does not care for her manners and resents her presence which is already interfering with his regimented but hedonistic lifestyle.
From the first scene, Blanche is nervous and jittery. She is reluctant to be seen in the glare of light and seems to have a drinking problem. She is also deceptive and is critical of her sister and brother-in-law.
Stanley later questions Blanche about her earlier marriage. Blanche had married when she was very young, but her husband died by suicide. This memory causes her obvious distress. The reader later learns she suffers from guilt due to the way she had reacted to finding out her husband's homosexuality and his fatal reaction. Stanley, worried that he has been cheated out of an inheritance, demands to know what happened to Belle Reve, once a large plantation and the DuBois family home. He tells Stella about the Napoleonic Code which, in those days, was a legal right of a husband over his wife's financial affairs. Blanche hands over all the documents pertaining to Belle Reve. While looking at the papers, Stanley notices a bundle of letters that Blanche emotionally proclaims are personal love letters from her dead husband. For a moment, Stanley seems caught off guard over her proclaimed feelings. Afterwards, he informs Blanche that Stella is going to have a baby.
The night after Blanche's arrival, during one of Stanley's poker games, Blanche meets Mitch, one of Stanley's poker player buddies. His courteous manner sets him apart from the other men. Their chat becomes flirtatious and friendly, and Blanche easily charms him; they like each other. Suddenly becoming upset over multiple interruptions, Stanley explodes in a drunken rage and strikes Stella. Blanche and Stella take refuge with upstairs neighbor, Eunice Hubbell. When Stanley recovers, he cries out from the courtyard below for Stella to come back by repeatedly calling her name until she comes down and allows herself to be carried off to bed. Blanche is shocked to see that her sister has returned to her husband right after he assaulted her. After Stella returns to Stanley, Blanche and Mitch sit at the bottom of the steps in the courtyard, where Mitch apologizes for Stanley's coarse behavior.
The next morning, Blanche rushes to Stella and describes Stanley as subhuman, though Stella assures Blanche that she and Stanley are fine. Stanley overhears the conversation but keeps silent. When Stanley comes in, Stella hugs and kisses him, letting Blanche know that her low opinion of Stanley does not matter.
As the weeks pass, the friction between Blanche and Stanley continues to grow. Blanche has hope in Mitch, and tells Stella that she wants to go away with him and not be anyone's problem. During a meeting between the two, Blanche confesses to Mitch that once she was married to a young man, Allan Grey, whom she later discovered in a sexual encounter with an older man. Grey later killed himself when Blanche told him she was disgusted with him. The story touches Mitch, who tells Blanche that they need each other. Mitch also has lost someone and seems to have empathy with Blanche's situation.
Later, Stanley repeats gossip to Stella from a seedy salesman with contacts in Laurel that Blanche was fired from her teaching job for involvement with an under-age student and that she lived at a hotel known for prostitution. Stella erupts in anger over Stanley's cruelty after he reveals he has already told Mitch. Later that evening, at Blanche's birthday party, there is an empty seat at the table for Mitch. Stanley gives Blanche a birthday "present", a one-way ticket back to Laurel by Greyhound bus. An argument ensues between Stella and Stanley, but is cut short as Stella goes into unexpected labor and is taken by her husband to the hospital.
As Blanche waits at home alone, Mitch arrives and confronts Blanche with the stories that Stanley has told him. She eventually confesses that the stories are true. She pleads for forgiveness. An angry and humiliated Mitch rejects her. Nevertheless, he demands sex from her, suggesting that it is his right since he has waited for so long for nothing. Blanche threatens to cry fire and tells him to get out.
Stanley returns home to find Blanche alone in the apartment. She has descended into another fantasy about an old suitor coming to provide financial support and take her away from New Orleans. She falsely claims that Mitch had asked for her forgiveness, but she had rejected him. Stanley goes along with the act before angrily scorning Blanche's lies, hypocrisy and behavior, and calling out her lie about Mitch. He advances toward her; in response, she threatens to attack him with a broken bottle, but is overpowered. Blanche collapses on the floor and Stanley is last seen taking her unconscious into his bed.
Some time in the near future, during a poker game at the Kowalski apartment, Stella and Eunice are seen packing Blanche's meager belongings while Blanche takes a bath in a catatonic state, having suffered a mental breakdown. Although Blanche has told Stella about Stanley raping her (which he denies), Stella cannot bring herself to believe her sister's story. When a doctor and a matron arrive to take Blanche to the hospital, she initially resists them and the nurse painfully restrains her. Mitch, present at the poker game, breaks down in tears. The doctor is far more gentle and she goes willingly with him, saying, "Whoever you are – I have always depended on the kindness of strangers." The poker game continues, uninterrupted.
