Nora is a 26-year-old crime novelist who lives a highly regimented, solitary life in London. Guarded and intensely private, she has spent the last ten years deliberately distancing herself from her hometown to suppress painful memories. Her carefully controlled existence shatters when she receives a surprise invitation to the hen weekend of an estranged childhood friend, forcing her back into a social circle she tried to leave behind.

Clare is Nora's former best friend from primary school and the bride-to-be at the center of the weekend's festivities. She works in public relations for the Royal Theatre Company and possesses a magnetic, charismatic personality that draws people to her. Despite her charm, she has a history of exerting dominant control over her social circles and maintaining a flawless public image at all costs.

Nina is a sharp-witted doctor who recently returned from volunteering with Médecins Sans Frontières in Colombia. She is Nora's only remaining link to her school days, having maintained their friendship while living in London. Reluctant to attend the hen weekend, she relies on her cynical sense of humor and alcohol to cope with the uncomfortable social dynamics at the Glass House.

Florence, commonly called Flo, is Clare's maid of honor and best friend from university. She hosts the hen weekend at her aunt's isolated, modern, glass-walled summer house in the woods. Intensely devoted to the bride-to-be, she painstakingly organizes the itinerary and becomes highly emotional whenever she feels anyone is ruining the celebration she meticulously planned.

James is the groom-to-be whose upcoming wedding serves as the catalyst for the weekend gathering in the dark woods. He is Nora's former high school boyfriend, a detail that deeply complicates the weekend's dynamics. A talented former actor, his presence hangs heavily over the narrative as Nora attempts to reconcile the boy she knew with the man Clare is about to marry.

Tom is a sophisticated playwright who works with Clare at the Royal Theatre Company. As the only male guest invited to the hen weekend, he brings a theatrical perspective to the gathering, often comparing the transparent Glass House to a stage set. He enjoys drinking and partaking in recreational drugs, adding to the unpredictable atmosphere of the weekend.

Melanie is a lawyer currently on maternity leave who became friends with Clare and Flo during their university years. Struggling with being away from her six-month-old baby for the first time, she is highly anxious about the lack of cell phone reception and landline access at the remote Glass House.

Detective Constable Lamarr is a steady police investigator tasked with unraveling the chaotic events that occurred during the hen weekend. She questions the survivors to piece together the incident, maintaining a careful distance while probing for inconsistencies in their stories.

Matt is a friend of the groom from their time at Cambridge. Serving as the best man for the upcoming wedding, he provides an outside perspective on the bridal couple's relationship and offers a link to the life the groom built after leaving his hometown.