Lucy is a teenager growing up in the conservative, small town of Crossmore, Ireland. She is highly observant and anxious about her social standing, often measuring her own behavior against the expectations of her community. Though everyone assumes she will eventually marry her childhood best friend, Martin, her attention shifts toward her female friend, Susannah. She struggles to reconcile her internal desires with the rigid, traditional life modeled by her parents.

Susannah is the daughter of a local socialite and lives in Croft Hall, a large home on the outskirts of Crossmore. Unlike her peers, she comes from wealth and a broken home, with an absentee father and a combative mother. She cares little for the conservative rules of her town and freely flouts social conventions. Her bold demeanor and indifference to gossip draw Lucy's intense fascination.

Martin is a good-natured teenager from a local farming family. He acts as the bridge between the town's groups of boys and girls, largely due to his close, lifelong friendship with Lucy. The town collectively assumes that he and Lucy will marry, an expectation he seems willing to fulfill. He serves as an anchor to Crossmore's traditional way of life.

Lucy's mother is a strict homemaker who previously worked in a bank before marrying and having children. She enforces traditional gender roles and expects her daughter to find a respectable husband. She relies heavily on social norms and is highly suspicious of any behavior that deviates from Crossmore's accepted standards.

He is a hardworking farmer who believes the land he works is cursed. He maintains a quiet presence in the household, leaving the discipline and domestic management entirely to his wife.

Tadgh is Lucy's older brother. He closely mirrors his father in both behavior and career trajectory, as he is slated to inherit the family's farm. He and Lucy are not currently close.

Ciaran is one of Lucy's younger brothers. He lives in the crowded Nolan household under the strict supervision of their mother.

Padraig is the youngest child in the Nolan family. As an infant, he requires constant care, which Lucy occasionally provides to avoid other household pressures.

Catríona is Susannah's mother. She frequently travels away from Croft Hall on weekend trips, leaving her daughter alone. She is highly concerned with her daughter's modesty and appearance but provides little emotional support.

Phil is Susannah's father. He lives in the city with his other children and rarely makes the trip out to Crossmore. He is mostly absent from his daughter's daily life.

Maria is the youngest of seven sisters and acts as the unofficial leader of Lucy's friend group. She possesses a rigid, pre-planned vision for her life. She frequently dictates the group's social rules and relies on her older sisters for gossip about the older students.

Eimear is a regular member of the Crossmore girls' group. She lives in a loud house filled with younger siblings. She adheres closely to the town's social norms and is quick to judge outsiders.

Patricia is considered the outlier of the main friend group. She deals with a highly stressful home life, as her father has early-onset dementia and her mother cares for five-year-old twins. She often directs her resulting frustration at the other girls.

Joan is a quiet but steady member of Lucy's friend group. She often accompanies the other girls to parties and sleepovers but prefers to go to sleep early rather than participate in late-night conversations.

Bernadette is one of the girls in Lucy's immediate social circle in Crossmore. She participates in the group's standard discussions about local boys and school dances.

Rita is a local girl who exists outside the main social hierarchy of Lucy's friend group. She develops an open crush on Martin, making her a target of vicious gossip from the other girls.

Geraldine is a woman Lucy meets and works with after moving to Dublin. She lives openly and comfortably with her identity, offering Lucy an example of a life completely detached from Crossmore's rigid expectations.

Evelyn is an older woman living in Dublin who quickly takes Lucy under her wing. She serves as a confidante and sounding board, openly dismissing the concept of sin and encouraging Lucy to contact the people she misses.

Deirdre is Eimear's mother. She runs a chaotic household and occasionally hosts events for the local teenagers.

Ms. O'Neill is a school teacher in Crossmore who harbors a petty grudge against Susannah. She publicly mistreats students she dislikes, using her position of authority to embarrass them.

Sorcha is Maria's older sister. She acts as the primary conduit of information for the younger girls, occasionally accompanying them on shopping trips for school dances.