Elizabeth is an unmarried middle-class woman who moves to the coastal town of Lyme Regis with her sisters. Possessing a sharp mind, she develops a passion for natural sciences and collecting fossilized fish on the local beaches. She finds that small-town life offers her more independence than London, allowing her to ignore rigid societal expectations and pursue intellectual satisfaction.

Mary is a bright, fiercely observant working-class girl living in deep poverty in Lyme Regis. Uneducated but deeply instinctual, she hunts "curies" on the treacherous beaches to support her family. Her sharp eyes and natural intuition allow her to uncover groundbreaking prehistoric skeletons that challenge the era's religious and scientific beliefs.

Margaret is the youngest and most conventionally attractive of the Philpot sisters. Known for wearing a signature green feathered turban, she deeply desires marriage and aligns herself with the social expectations of 19th-century middle-class women. She eventually finds purpose creating a popular healing salve for the villagers.

A handsome, charming retired lieutenant who collects fossils for personal glory rather than scientific inquiry. He relies on his charisma and wealth to acquire specimens found by skilled hunters. His arrival in Lyme Regis stirs up romantic tension and exposes the strict class divides of the era.

The widowed mother of Mary and Joe. Living in deep poverty and having lost many children, Molly is fiercely practical and unsentimental. She manages the business of selling fossils, proving herself to be a fearless negotiator when dealing with wealthy gentlemen who assume they can cheat her.

One of Elizabeth's unmarried sisters who moves to Morley Cottage in Lyme Regis. She is quiet, content with small-town life, and immerses herself in tending the cottage gardens while her sisters pursue fossils or social engagements.

Mary's older brother who initially helps hunt for skeletons to support the family. He eventually tires of the dangerous, unpredictable work on the cliffs and seeks financial stability by becoming an upholsterer's apprentice.

An eccentric, free-spirited Oxford scholar and fossil enthusiast who visits Lyme Regis. Unlike many gentlemen of his era, he treats Mary with genuine intellectual respect and engages seriously with her questions about the natural world.

Mary's childhood friend from the dissenter chapel. Fanny views fossils as demonic or fairy-created, reflecting the strict religious fears of their community. Her fear and adherence to social rules eventually drive a wedge between her and Mary.

The wealthy Lord of Colway Manor who owns the land where Mary finds major fossils. He views fossils merely as showpieces and exploits his class advantage to claim credit for Mary's discoveries.

Mary's father, a cabinet maker who supplements his income by gathering and selling curies. His sudden death from a cliff fall leaves his family destitute and forces Mary to become the primary fossil hunter.

A notoriously lazy and aggressive fossil hunter in Lyme Regis. Real name William Lock, he prefers stealing other people's discoveries over doing the hard labor himself, posing a constant physical threat to Mary.

A wealthy gentleman who briefly courts Margaret Philpot before abandoning her because her family lacks sufficient wealth and social standing.

Elizabeth's brother and former legal guardian. His marriage forces his unmarried sisters to leave their London residence and establish their own lives in Lyme Regis.