Lilian is a 25-year-old apprentice bookbinder living in Oxford with her widowed father. She is an artisan who values the tactile craft of books. Driven by financial precarity and a desire for independence, she takes on extra commissions. Her attention to detail pulls her into a complex mystery surrounding a burned book and hidden letters.

Caxton is a master bookbinder operating a workshop in Oxford. He serves as a paternal figure to Lilian, teaching her the artisan trade while offering guidance and occasional reprimands. He is deeply supportive of Lilian's talents and hopes to pass his legacy to her.

Harry is Lilian's childhood friend and former sweetheart who works locally in Oxford. After years of distance following the end of their relationship, he re-enters Lilian's life. He wants to support Lilian even when her actions confuse or worry him, demonstrating a protective instinct.

Isabel is an intelligent, stubborn young aristocratic woman living in 1851. As the daughter of a wealthy and powerful lord, she is expected to marry for political and financial advantage. Instead, she seeks her own destiny and fiercely resists her father's attempts to control her life.

Julia Chatton (Mrs. Chand) is a woman with ties to the Chatton family. She shows a keen interest in the novels of Abel Bell and the specific binding marks found within them. She views the preservation of her family's lineage as paramount, driving her to extreme measures.

Devlin is a sinister, bowler-hatted man who aggressively pursues the remaining copies of the Abel Bell novels. He resorts to threats, intimidation, and physical violence to obtain the books, operating with a detached, materialistic attitude on behalf of a wealthy client.

Malcolm Chatton is a wealthy, self-made lord in the 1850s. He views his daughter primarily as a tool to consolidate his wealth and power through an advantageous marriage, responding with cruelty and threats when she attempts to assert her independence.

Charlie is a young assistant working in Edmund Grieves's bookshop in London. He is emotionally uncomplicated, observant, and eager to help Lilian navigate the confusing circumstances surrounding the mysterious books connected to his employer's shop.

William is a curious, intellectual young man from a modest background. He enjoys word puzzles and reading novels by Abel Bell. His charismatic nature draws Isabel to him, and he acts boldly in an attempt to secure a future together despite their class differences.

Lilian's father runs a faltering bookshop in Oxford. Following the death of his wife, he turned inward and accrued substantial debt, leaving the business financially precarious. Despite his struggles, he shares a deep love of books with his daughter.

Dr. Ashburn is a renowned physician and wealthy book collector living at Tynesdale House near Bath. He unwittingly initiates Lilian's investigation when he gives her a fire-damaged book he received in a shipment from a London bookseller.

Mohan Chand is a London-based bookbinder who possesses one of the mysterious Abel Bell novels. He uses a specific binder's mark hidden beneath back endpapers and fiercely guards his wife's collection of rare books.

Grieves is a defensive London bookseller with a reputation for pressuring collectors. He was commissioned to acquire a set of six books written by Abel Bell but grew fearful of the project, insisting the books are cursed and trying to rid his shop of them.

Silas is Malcolm's volatile and dangerous brother. He holds considerable wealth and becomes fixated on seeking vengeance following family tragedies, employing men to violently enforce his will.

Ambrose Fane is an eccentric, wealthy book collector living in a decadent home in Birmingham. He possesses an extensive collection of rare, esoteric, and erotic volumes, including one of the six matching Abel Bell books.

Henry Montague is the eccentric elderly publisher of the Abel Bell novels. Operating out of Manchester, he fields inquiries from obsessed fans while protecting the true identity and location of his most mysterious author.

Deidre is a 74-year-old woman who began writing under the masculine pseudonym "Abel Bell" at age 18. She lives a secluded life on the Dorset coast, preserving the secret of her authorship to maintain her literary success in a male-dominated field.

Agnes is Deidre's granddaughter and collaborative writing partner. She continues the work of writing the Abel Bell adventure novels, maintaining the family pseudonym in a mutually supportive, apprentice-master dynamic.

Daisy is Isabel Chatton's loyal maid and lifelong companion. She assists Isabel in sneaking out to social events, exchanging secret letters, and selling jewelry to fund Isabel's attempts at independence.