A dedicated used book dealer operating out of New York City, finding inventory at local estate sales. Raised by a single mother after his father disappeared, Apollo is fiercely determined to be an attentive, hands-on father to his own newborn. He obsessively documents his parenting milestones on social media. He seeks community approval while coping with recurring childhood nightmares about his absent father.

An organized librarian with a passion for Brazilian cinema and a strong independent streak. Having survived a childhood tragedy, she relies heavily on her older sister for support. As a new mother, Emma experiences severe exhaustion and anxiety. She withdraws from her husband as she becomes convinced something is terribly wrong with her baby.

A tech-savvy individual who enters Apollo's life through a parole-mandated therapy group. He presents himself as an estranged husband seeking to reconcile with his family. He bonds with Apollo over rare books and offers his computer skills to help Apollo during a period of crisis.

A New York parole officer who courts Lillian and becomes Apollo's father. He leaves the family when Apollo is four years old, leaving behind a mysterious box labeled "Improbabilia" that contains a children's book. His sudden absence leaves a lasting void in his son's life.

A Ugandan American immigrant who survived the loss of her cousin to paramilitary violence before moving to New York. She is a practical, protective mother who raises Apollo alone. She actively encourages his early interest in books by bringing reading materials home from her office.

The newborn son of Apollo and Emma. His unexpected arrival on a stalled subway train brings joy to Apollo but triggers intense anxiety in Emma. He soon becomes the focal point of mysterious occurrences involving vanishing photographs and strange messages.

Emma's older sister and a professional midwife. After their parents died in a house fire, Kim raised Emma and remains her closest confidante. She provides medical care and emotional grounding during Emma's pregnancy and postpartum struggles.

An Iraq War veteran who transitioned into a career as a bookseller after studying library science. He maintains a pragmatic, no-nonsense approach to business. He serves as a loyal sounding board for Apollo's personal and professional worries.

The pragmatic leader of the Wise Ones, a group of women living off the grid in abandoned hospital buildings on North Brother Island. She uses puppetry to explain old fairy tales and offers sanctuary to mothers facing extraordinary crises.

An elderly man of Norwegian descent who lives in a heavily heated house in Queens. He frequently visits the local forest to leave specific food offerings, operating under the burden of deep-seated ancestral traditions and folklore.

A fearful woman hiding within the community on North Brother Island. She remains highly guarded and terrified of being found, carrying deep trauma from the loss of her eldest child.

Emma's childhood friend who works as a writer. She understands Emma's willful nature and shares insights with Apollo about Emma's past adventures in Brazil.

Patrice's romantic partner. She is observant and caring, reaching out to Apollo's mother when she becomes concerned about his well-being.

A local parish priest who facilitates a support group called the Survivors. He attempts to provide spiritual comfort to grieving parents in his community.

The superintendent of Apollo and Emma's apartment building. He performs wellness checks on the residents and holds deep sympathies for the Kagwa family.

A Ukrainian American widow living in Queens. She insists on closing a deal with Apollo, ultimately selling him a rare book for a very low price out of a mutual sense of pity and persistence.

A young girl living among the Wise Ones. She is independent but eventually accepts Apollo's help with a scooter, providing him with a rare moment of connection.