Opaline is a 21-year-old book lover living in 1921. She cuts her hair short to defy traditional expectations and travels to France to avoid an arranged marriage. Guided by a deep appreciation for literature instilled by her late father, she actively pursues a career as an independent rare book dealer. She makes quick, decisive choices to maintain her freedom.

Martha is a young woman fleeing domestic violence who finds refuge in a basement flat on Ha'penny Lane. She possesses an unexplained ability to read the histories and emotions of the people around her. Mysterious lines of an unknown story frequently appear in her mind, which she feels compelled to tattoo on her back. She struggles with indecision and self-worth due to her traumatic past.

Henry is a PhD student from England researching lost literary works in Dublin. His obsessive drive to discover a rare Emily Brontë manuscript stems from a desire to achieve professional recognition. He hopes academic success will repair the feelings of inadequacy caused by his turbulent childhood.

Lyndon manages the Carlisle family affairs following the death of their father. He is a World War I veteran known by the moniker 'The Reaper' for his ruthless command. He expects total obedience from his household and attempts to force his sister into an advantageous marriage for financial gain.

Armand is a Moroccan-born rare book dealer operating in Paris. He uses his flirtatious charm to mask a ruthless business ambition. He operates in the cutthroat world of book collecting, prioritizing profit and acquisition above personal attachments.

Madame Bowden is an elderly woman with eccentric habits who resides at 12 Ha'penny Lane. She behaves like a glamorous old-world actress who never stops performing her chosen role. She seemingly knows more about the mysterious properties of her house than she admits to others.

Shane is Martha's estranged husband. He initially appeared supportive when they met at a technical college. He systematically isolated Martha from her support network and used physical violence to maintain dominance over her life.

Martha's mother is a quiet woman who communicates entirely through sign language. Her silence creates a barrier between her and her daughter. Martha fears that her mother judges her for enduring an abusive marriage.

Josef is an Austrian mechanic held in an Irish prisoner of war camp during World War II. Because of Ireland's neutrality laws, he is permitted to leave the camp to attend university courses. He frequently visits the bookshop to escape the realities of the ongoing conflict.

Sylvia is an American-born expatriate who owns the famous Shakespeare and Company bookstore in Paris. She acts as a central figure for the artists and intellectuals of the Lost Generation. She supports emerging writers and teaches newcomers the intricacies of the rare book trade.

Matthew is the son of an antiques dealer who recently passed away. He honors his father's legacy by maintaining the property built from a dismantled Italian library. He offers Opaline a chance to establish her own business on a trial basis.

Isabelle is Henry's fiancée living in England. She remains largely separated from his daily life in Dublin while he conducts his academic research.

Henry's father is an alcoholic whose past behavior fractured his family. He once sold a valuable J.R.R. Tolkien letter that Henry discovered, using the money to fund his addiction. He recently entered a rehabilitation program.

Lucinda is Henry's sister in England. She serves as the primary bridge between Henry and their estranged father. She prepares to welcome her new baby while advocating for family unity.

Mary is a young woman who endures severe hardship. After suffering abuse at the hands of a priest, her father beat her and sent her to an institution to hide the scandal.

Logan is a student at the local college in Dublin. He attends literature courses and provides Martha with a sense of normalcy in her academic pursuits.