Clara is a thirty-three-year-old art teacher and children's book illustrator. Following a financially ruinous divorce, she lives in her childhood home with her father and young daughter. She attempts to maintain a quiet, orderly life, but remains deeply haunted by the sudden disappearance of her mother twenty-five years earlier. A surprise phone call from a British stranger upends her routine and forces her to cross the Atlantic in search of answers.

Bronwyn was a literary child prodigy who published the famous children's novel *The Middle Place* at twelve years old. As she grew older, her intensely vivid imagination and unconventional behaviors led to traumatic institutionalization in a psychiatric hospital. Fearful of being locked away again after a tragic house fire, she vanished into the night when Clara was only eight years old, taking nothing but a leather satchel full of her invented language.

Charlie is a British musician living in London who is actively grieving the recent loss of his father. While sorting through the estate, he finds a hidden satchel containing an invented language dictionary and a letter addressed to Clara Harrington. Rather than ignoring the discovery, he tracks Clara down and offers to help her solve the mystery of her mother's missing pages.

Wynnie is Clara's eight-year-old daughter. She faces bullying at school due to her distinct physical traits and weak lungs, relying heavily on an imaginary friend named Emjie for comfort. She accompanies her mother on the transatlantic journey to England, where her fragile health immediately suffers under the thick London smog.

Callum was Charlie and Archie's father and Pippa's husband. He died three weeks before the events of the novel begin. A man who valued stories and language, he possessed a secret connection to Bronwyn's past, evidenced by the leather satchel he kept hidden in his study.

Timothy is Clara's father and Bronwyn's husband. He works as a surgeon in South Carolina and maintains the family home in Bluffton. Following his wife's disappearance and his daughter's difficult divorce, he serves as a steadying, practical force for Clara and Wynnie.

Nat is Clara's ex-husband and Wynnie's father. Struggling with a severe gambling addiction, he drained Clara's life savings during their divorce, destroying her aspirations of opening an art school for children. His unreliable presence continues to cause stress for his daughter and ex-wife.

Pippa is Callum's widow and the mother of Charlie and Archie. Following the recent death of her husband, she retreats to the family's property in Cumbria, where she finds comfort in community theater and painting.

Archie is Charlie's twin brother. He acts as a grounding presence for Charlie as the family navigates the aftermath of Callum's death and Charlie's personal romantic troubles.

Moira works as a maid for the Jameson family. She held a deep affection for Callum, viewing him as a father figure, and travels with Charlie, Clara, and Wynnie as they flee the suffocating smog of London for the countryside.

Lilia is Clara's best friend in Bluffton. When Clara struggles with the decision to travel overseas and uproot her life, Lilia acts as an enthusiastic sounding board and urges her to seize the opportunity.

Eliza is an author based in Maine who writes the "Harriet the Hedgehog" children's books. Clara illustrates her work, though the two have maintained a strictly long-distance professional relationship without ever meeting in person.

Finneas is a friendly British traveler returning home. Upon hearing Clara and Wynnie's story, he recommends they visit his home region of Cumbria, pointing out local connections to Bronwyn's literary work.

Martha is Bronwyn's mother, who initially nurtured her daughter's prodigy-level talents. However, when Bronwyn's imagination became overwhelming during her teenage years, Martha had her institutionalized in a psychiatric hospital, deeply fracturing their relationship.

Brian is Bronwyn's abusive former boyfriend from her youth. Following their difficult breakup, he penned *Child Genius*, an unauthorized and uncharitable biography that Clara and Timothy heavily resent.

Dr. Finlay is a local physician whom Charlie contacts to treat Wynnie's severe respiratory distress. He advises Clara to move her daughter away from the toxic London smog for her health and safety.