Alice is a twenty-five-year-old writer from a small Oregon town. Shy and reserved since childhood, she relies on reading and eventually writing to understand the world around her. She processes her personal grief by swimming and working on her first novel, a book called Theo. Her manuscript eventually reaches a wide audience and connects strangers across the country.

Lara is an assistant at a New York literary agency who has recently become a stay-at-home mother. Originally planning to pursue a doctorate, she shifted to the publishing industry after meeting her husband and discovering her talent for evaluating manuscripts. Feeling isolated by the heavy demands of new motherhood, she finds validation and comfort when she reads the opening pages of Theo.

Rowan is a former screen actor who left Hollywood after developing a progressive skin condition that altered his appearance. Retreating to a quiet life in Canada, he builds a second career narrating audiobooks. He approaches his voice work methodically, but recording Theo moves him emotionally and disrupts his carefully maintained isolation.

Miranda is a twenty-eight-year-old mixed-media artist living on an island in Washington State. She constructs three-dimensional art from scavenged materials and sea glass. She aggressively protects her creative freedom and resents her mother's focus on commercial success, leading her to stubbornly repurpose the pages of a gifted novel for her latest sculpture.

Tyler is a former competitive free-diver who has relied on the water as a psychological escape since he was a young boy. After suffering a severe stroke during a deep dive, he is medically barred from the water, which causes depression and short-tempered behavior. He turns to reading a novel left behind by his ex-girlfriend to find the emotional release he usually gets from diving.

Nola is an unhoused high school student attempting to survive under the radar. Following the traumatic death of her father and her mother's subsequent disappearance, she uses books and the public library to distract herself from her harsh reality. A defensive and intelligent teenager, she protects the story of her life until an English assignment forces her to confront her anger.

Kit is a content bookseller who loves matching readers with the right stories. Unlike many of his peers, he has no ambition to write; he simply loves books. He seeks emotional order by dating a highly logical scientist, but reading Theo forces him to realize he is stifling his somewhat chaotic personality to appease his family and partner.

William is a sixty-two-year-old retired civil engineer overwhelmed by grief following the death of his adventurous wife. Seeking a drastic change, he sells his home and accepts an isolated caretaking position in the mountains. When a severe winter storm traps him indoors, he relies on his late wife's annotated books to maintain his will to survive.

Juliet is a Southern California intimacy coordinator who choreographs film sex scenes with the precision of stage combat. She turned her childhood fascination with theatrical duels into a successful career. Though she enjoys a stable family life, she experiences a moment of domestic dissatisfaction that she works through while listening to a familiar voice on an audiobook.

Madeline is a veteran literary agent who has dedicated over fifty years of her life to the publishing industry. After suffering a fall and receiving a terminal neurological diagnosis, she confronts her impending loss of independence. She lives alone in a narrow, multi-story townhouse entirely filled with books, which serve as physical monuments to her long career.

Saylor is an independent woman who avoids heavy expectations. She dates Tyler but ultimately leaves him when his depression following a diving accident becomes an emotional wall she cannot breach. Her discarded copy of Theo impacts Tyler's recovery.

Peter is Alice's older brother. He initially serves as her closest confidant, but the heavy pressure of family expectations drives him to drop out of college and travel alone. His struggles with addiction and tragic early death shape Alice's adult life.

Professor Roberts is a supportive college instructor in Maine. He possesses a gentle demeanor and provides critical guidance to Alice, teaching her to write with empathy. He connects her with the publishing world by introducing her work to his old friend in New York.

Annalise is an accomplished scientist whose work involves the atomic clock. She has a clear, precise personality with smooth emotional surfaces. Her logical nature initially appeals to Kit, but her inability to engage with his family's chaotic energy highlights the cracks in their relationship.

Ms. Hildegrand is a high school English teacher who pays close attention to her students. Having grown up in foster care, she recognizes the signs of neglect in Nola and steps in to offer her practical help and housing.

The school groundskeeper who notices Nola secretly living in his work shed. Rather than reporting her to authorities, he confides in his childhood friend from the foster system to find Nola a safe living arrangement.

Abigail is William's late wife, a woman who loved literature and greeted life's surprises with a spirit of adventure. Her terminal cancer diagnosis fractures her family, but her annotated books continue to guide her husband long after she is gone.

Clara is William and Abigail's grown daughter. She honors her mother's difficult medical requests regarding terminal illness, a burden that creates a painful rift between Clara and her grieving father.