I guess the central thing is the messy, overlapping relationships. The narrator is Frances, a 21-year-old college student in Dublin who writes poetry and performs spoken word with her best friend (and ex-girlfriend) Bobbi. They meet Melissa, a slightly older writer, and Frances begins an affair with Melissa's husband, Nick, a handsome but depressed actor. So it's this quartet: Frances and Nick's secret, intense sexual relationship, Frances's deep, complicated friendship with Bobbi, and the unsettling friendship/mentorship between Frances and Melissa, who seems to know more than she lets on.
The plot is driven by the emotional fallout more than big events. Frances uses the affair as a way to feel something while also dealing with her own self-destructive tendencies, financial worries, and a distant father. It's less about 'will they get caught?' and more about the psychological toll of the secrecy and the power imbalances. The 'conversations' in the title are key—the witty, analytical talks between the four of them, and the internal monologue in Frances's head that's so much sharper and more vulnerable than what she says aloud. The ending is deliberately unresolved; it feels like everyone is rearranged but not fixed, which fits the whole mood.