Hannah, an aspiring writer, is stunned when her parents announce on a visit to New York that they are cutting her off financially. They've been supporting her for the two years since she graduated from liberal arts college, and she needs one "final push" in order to realize her full potential as a writer.
Meanwhile, Hannah's roommate and best friend Marnie seemingly has it all together, with a very adult job at an art gallery and a long-term boyfriend. But she's beginning to question whether Charlie, who appears to be the perfect guy, is actually perfect for her. She's also worried about being able to pay the rent now that Hannah's been cut off, and urges Hannah to demand that her internship at the literary magazine be turned into a paying job.
When Hannah approaches her boss with her request, she's let go rather than given what she wants. She seeks solace from Adam, the triple threat actor-writer-woodworker with whom she sleeps - at least when he decides to answer her texts. She apparently takes comfort in his dirty talk and critical comments about her body, because she ends up staying way too late and misses the start of the dinner party she and Marnie are throwing to welcome their friend Jessa back to town.
Jessa, their free-spirited, beautiful, British friend, is just returning from her latest travels abroad (nannying in France, shucking pearls in Bali) and moving in with her younger cousin Shoshanna, a naïve NYU student with ‘Sex and the City' dreams. Hannah and Marnie are throwing Jessa a welcome home dinner, though with Hannah off in Adam-land and Jessa late to her own party, Marnie is stuck entertaining only Charlie, his friend Ray and the girl he met that morning who's not really into eating this week.
When Hannah finally makes it home, she drinks some of the opium tea that Ray brews up (it's legal, like flowers) and decides to confront her parents before they return to Michigan. Jessa advises her that she just needs to explain once and for all that she is an artist, while Marnie reasons that she simply needs to ask them for a little more support until she finds a job. As Hannah, who has declared that she just may be the voice of her generation, is forcing her parents to read the pages of her memoir at the foot of their hotel bed, the opium tea kicks in. She ends up half-passed out on the floor as her parents argue over their decision to cut her off.
Back at the dinner party, Marnie and Jessa disagree about how to deal with Hannah. Jessa finds Marnie uptight and mothering, while Marnie finds Jessa too carefree, even careless - at which point Jessa reveals that she is pregnant, and probably not on purpose.