Helen is a pregnant woman living in her childhood mansion in the upscale London neighborhood of Greenwich Park. Having experienced four miscarriages, she strictly follows pregnancy health guidelines and desperately hopes for a safe delivery. She relies heavily on her husband and her older brother's family for social stability, though her early maternity leave leaves her feeling isolated and anxious.

Daniel is an architect working at a firm alongside Helen's brother, Rory. He is currently stressed and working long hours to manage the backlash against a controversial luxury housing development. He presents as a responsible, professional husband who is deeply affected by his and Helen's previous pregnancy losses.

Rachel is an unconventional expectant mother who dismisses standard pregnancy health guidelines, openly smoking and drinking alcohol. She quickly befriends Helen and inserts herself into Helen's daily life, appearing unannounced at various locations. Her intrusive questions about Helen's family make her a mysterious figure in Greenwich Park.

Rory is Helen's older brother and the head of the family architecture firm that he inherited from their father. He lives near Helen in Greenwich Park and enjoys a wealthy, comfortable lifestyle. He faces professional scrutiny due to negative press surrounding his firm's new housing development.

Serena is Rory's wife and Helen's glamorous sister-in-law. She is a professional photographer with expensive taste, a curated aesthetic, and a large social circle. Pregnant at the same time as Helen, Serena projects an image of upper-class perfection that Helen frequently tries to emulate.

Katie is Helen's childhood friend and a working journalist. She is deeply invested in covering a sexual assault trial involving wealthy defendants, attempting to give the young survivor a voice. She maintains a complicated, on-and-off romantic connection with Helen's younger brother.

Charlie is Helen and Rory's younger brother. He works nights at a music club, lives in a working-class neighborhood, and shares custody of his young daughter. Helen frequently judges his lifestyle and past mistakes, viewing him as irresponsible compared to Rory and Daniel.

Jane is Rachel's former roommate. She lives in a deteriorating building and provides Katie with background information about Rachel's employment history and odd habits before Rachel moved out.

John is Rachel's father, who travels from Cambridge to search for answers regarding his daughter's recent activities. He worries about her safety and attempts to piece together her life in London.

DCI Carter is an experienced detective nearing retirement. He reluctantly assists Katie with her journalistic inquiries, sharing her frustrations with how the justice system treats assault survivors.

Lisa works as a secretary at the architecture firm run by Rory and Daniel. She occasionally attends social events with her employers and their families.

Emily is a young woman involved in a high-profile court case against two wealthy men. She communicates with Katie about the possibility of sharing her personal story with the press after the trial concludes.

Ruby is Charlie's young daughter, who attends school in Hackney. She is the center of her father's daily routine, participating in various local activities like Brownies and football.

Maja is Charlie's ex-partner who lives near him in Hackney. The two maintain an amicable relationship to facilitate an easy co-parenting arrangement for their daughter.

Vilmos is a contractor hired to remodel Helen and Daniel's large home in Greenwich Park. He deals with structural issues regarding the property's cellar and concrete work.