In the summer before their final year at Trinity College, Frances and her best friend Bobbi meet an impressive local writer, Melissa. Bobbi quickly develops a crush on Melissa but Frances is unexpectedly drawn to Melissa's husband, Nick.

At Melissa's birthday party, Frances finds herself alone with Nick. They can't resist the attraction between them. The next day Frances visits her parents in the country and agonizes over what this turn of events might mean.

Back in Dublin, Frances and Nick meet to discuss things, and their attraction deepens. Things become complicated when Nick travels to Scotland for work. Frances is unable to confide in Bobbi and their relationship suffers.

Frances and Bobbi travel to Croatia to join Melissa and Nick on holiday. Having not spoken to Nick in a few weeks, Frances learns he has had a tough time recently, and they both realize that they are still attracted to each other.

As Frances and Nick grow closer, things become tense between Bobbi and Frances. Bobbi can sense Nick's attraction to Frances and becomes frustrated with Frances's reluctance to talk about it. A visit from Melissa's agent raises tensions.

In Ireland, tensions remain unresolved with Bobbi. Frances visits her mother but ends up in hospital when she experiences severe abdominal pain. Before returning to Dublin, she visits her father and is confronted by his growing alcoholism.

As the final year at Trinity begins, Bobbi is looking for a room to rent and Frances asks her to move in. Nick returns from Croatia. He and Frances contemplate being more open about their relationship, which excites and frightens her.

At Melissa's book launch, Frances struggles with her growing feelings for Nick. Her jealousy frustrates Bobbi. Feeling alone, Frances seeks intimacy, but the reality of her feelings for Nick cause her to behave in a destructive way.

Frances writes her first short story. Her health is still causing problems and she collapses at school. Bobbi brings her home, and as Frances recovers they talk more honestly about their friendship. Nick makes a surprising revelation.

Frances sees a consultant and is given a distressing diagnosis. This news, combined with an upsetting revelation from Nick and an unexpected argument with Bobbi, causes Frances' life to spiral out of control.

Frances faces the consequences of her actions and attempts to repair her relationship with Bobbi. She also finds a fragile understanding with her parents. As she strives to take control of her life, the question of her and Nick remains.