The play begins with a current-day (1940s at the time) Tom explaining to us that the play is his memory (1930s) being re-told, and has lots of funky memory elements in it like weird lighting and music. We are also introduced to a large screen that Williams uses to project images and pictures on as the play progresses. Tom explains that his father happily abandoned them years ago. We see Tom having dinner with his mother, Amanda, and his sister Laura. Amanda expresses a desire for Laura to have "gentlemen callers" (a.k.a. dates) as she used to, back when she was a Southern Belle.
Laura describes a boy named Jim she used to have a thing for in high school, and we see her glass menagerie obsession. Amanda gets angry at Laura for dropping out of a typing class due to her painfully shy nature.
The conflict with Tom is quickly established; he is at odds with his mother because he hates his job and wants to leave, but has a duty to support the family. His mother calls him selfish for his constant reading, dancing, drinking, and escaping to the movies. Laura encourages them to make up, which they do – ostensibly. But the issue is unresolved.
Amanda asks Tom to get a gentleman caller for his sister, which he does – one of his friends from work that turns out to be the Jim that Laura had spoken of. Amanda gets all excited and prepares the house. When Laura finds out that it’s Jim coming to visit, she hides in the living room. Jim, however, talks to her and gets her to open up. They bond; they kiss; Jim is engaged to someone else. He takes off, Laura gets sad, and Amanda yells at her son and then comforts Laura during Tom’s closing speech to the audience. Tom reveals to us that he abandoned his family shortly after that night, but has been haunted by Laura, the sister he abandoned, ever since.