The morning after, Blanche fearfully returns to the apartment to find her sister luxuriating in bed. Blanche had spent the night worried sick about Stella, but the conflict of the previous night was forgotten by its participants as soon as they were back in each other's arms. Stella admits that she is rather thrilled by Stanley's violent streak, and Blanche is horrified.
Blanche attempts to convince Stella that she can get out of her situation, but Stella insists that she is not in anything she wished to get out of. Blanche doesn't really hear her, though, and brainstorms an escape plan involving wiring an old beau for money. She calls Western Union, but can't think of what to say. The focus shifts, and it becomes clear that Blanche's concern for finances is just as much for herself as for Stella – she is completely broke.
Blanche continues to try to convince Stella to leave, but Stella is firm – she is happy. It doesn't matter whether or not Blanche understands, because all that matters to Stella is her relationship with Stanley. Blanche puts a name to it – desire – and compares it to the street-car of the same name. Stella asks whether Blanche had ever ridden on that street-car, and Blanche admits that she has, that it's what brought her here. Stella tells her to stop being so superior in that case, but Blanche still thinks such emotions are the stuff of brief affairs, not a marriage and a life.
Blanche gives a speech telling her opinion of Stanley as common and animalistic, while Stella listens wearily. Stanley arrives home, unnoticed by the women, and listens in on this speech. Blanche compares Stanley to a caveman, his poker night to a party of apes, and exhorts Stella not to regress to Stanley's primitive level but to evolve into a higher level of human.
After listening to Blanche's speech, Stanley steps out and steps back in, this time making his presence known and pretending he had just arrived. In response to Blanche, Stella embraces her husband plainly. Stanley grins at Blanche as she watches.
Scene 4 gives us the logical extension of the end of Scene 3 – the morning after, Stella is floating on a cloud of post-coital bliss, while Blanche continues with the same bluster of contradictory emotions she felt the night before. Blanche looks at Stella's situation and sees a damsel in distress, in need of rescuing, but Stella has long forgiven Stanley for his behavior. In fact, she admits that she likes his violence – when he smashed the lights with the heel of her slipper on their wedding night, it gave her a thrill.
The sisters' conversation goes round and round as Stella keeps insisting that she is happy and Blanche remains convinced that Stella is deluded. It is a troubling scene that can be played several ways – who is right? Is this domestic violence, and only Blanche is able to see that Stella is in a dangerous situation where she cannot make decisions for herself? Or is this really just the nature of the Kowalskis' relationship, and Blanche is too frigid to comprehend the couple's chemistry? The play as a whole seems to side with Stella, up until the moment Stanley crosses the line in Scene 10. For now, however, Blanche appears to be seeing what she wants to see – her baby sister mesmerized by the brutish Pollack – despite Stella's protestations.
The hypocrisy of Blanche's position is made very clear in the important dialog exchange about desire, both the concept and the street-car:
Blanche: What you are talking about is brutal desire – just – Desire! – the name of that rattle-trap street-car[…]
Stella: Haven't you ever ridden on that street-car?
Blanche: It brought me here – where I'm not wanted and where I'm ashamed to be.
Stella: Then don't you think your superior attitude is a bit out of place?
It is clear to both the audience and the characters themselves that they are discussing the streetcar Desire as a metaphor for the kind of desire that brings two people together. Each line of this exchange can be read in two ways – is Stella saying Blanche should drop her attitude as she knows she's not wanted at the Kowalskis' flat? Or that she should understand Stella's position because she too has felt crippling, damaging desire?
Blanche presents herself as a romantic throughout the play, clutching to notions of star-crossed lovers and gentlemen sweeping ladies off their feet. But when faced with a true love story, she balks. Blanche's kind of romance can't happen in the gutter. In theory, Blanche should see her sister's marriage as an epic love story between the princess and the commoner. But the truth is that Blanche's romanticism is a cover for the true cynicism of one who loves only calculatingly, for money and power and security. Of the DuBois sisters, Stella is the romantic.