Ned is the younger son of a prosperous merchant family in Kingsbridge. Following the destruction of his family's fortune, he finds himself working for Princess Elizabeth, eventually becoming one of her most trusted advisors in her secret service. He is defined by his deep commitment to promoting religious tolerance, firmly believing that individuals have the right to choose their own beliefs without facing violence.

Margery is a strong-willed and devoutly Catholic young woman from a socially ambitious Kingsbridge family. She frequently feels torn between her religious convictions and her duty to her parents, conflicting with her personal desires. Despite her family's manipulative tactics, she tries to follow her faith and seeks to preserve Catholic practices in an increasingly Protestant England.

Rollo is Margery's older brother, a fiercely ambitious and devoutly Catholic man from Kingsbridge. He prioritizes his family's social standing and wealth above personal connections, often viewing others as mere tools for advancement. His rigid worldview and deep-seated animosity toward Protestants place him in direct opposition to advocates of religious tolerance.

Sylvie is the brave and dedicated daughter of a Protestant bookseller in Paris. Deeply enmeshed in the clandestine Protestant community, she takes considerable risks to distribute illegal religious texts, including French Bibles. She is characterized by her unwavering faith and her protective instincts toward her community.

Pierre is a cunning, socially ambitious confidence man operating in Paris. Driven by an insatiable desire for power and noble status, he leverages his skills in deception to work as a spy for the powerful Catholic Guise family. He views relationships purely strategically, lacking genuine emotional attachment to the people he manipulates.

Mary is the Queen of Scots, living in France during her youth. Poised to marry Francis, the heir to the French throne, she is a central figure in the shifting religious and political alliances of Europe. She relies heavily on her trusted ladies-in-waiting to survive court intrigue and plot her political future.

Elizabeth is the Protestant heir to the English throne, facing intense scrutiny and danger during the reign of her half-sister, Mary Tudor. Highly intelligent and politically astute, she seeks to establish a realm where religious tolerance can prevent endless bloodshed, relying on advisors like Ned Willard to handle threats against her crown.

Barney is Ned’s older brother, an adventurous young man living with relatives in Spain. Uninterested in the family's traditional merchant business in Kingsbridge, he dreams of a seafaring life. He is charismatic, frequently engaging in romantic flirtations, but finds himself increasingly constrained by Spain's strict religious and social atmosphere.

Ebrima is a West African man enslaved by Carlos Cruz, working as an iron-maker in Seville. Outwardly practicing Catholicism to survive, he privately maintains the traditional spirituality of his homeland through covert water rites. He is highly skilled in metallurgy and desires to live as a free man despite the oppressive systems surrounding him.

Alison is the fiercely loyal childhood friend and lady-in-waiting to Mary Stuart, the Queen of Scots. Skilled in political maneuvering within the French court, she frequently offers Mary pragmatic advice, even when her guidance goes against the queen's wishes. Her life is entirely dedicated to protecting and serving her monarch.

Alice is Ned and Barney's mother, serving as the leading merchant in Kingsbridge. Astute and protective of her family's interests, she maneuvers through treacherous financial waters after the loss of Calais and pushes back against the ambitious Fitzgerald family to preserve her livelihood. She harbors an innovative vision to convert the ruined Kingsbridge Priory into an indoor market.

Reginald is the patriarch of the Fitzgerald family. Desperate to elevate his family's social standing and financial security, he orchestrates his daughter's advantageous marriage and ruthlessly pursues business ventures, often at the expense of others in Kingsbridge.

Bart is the son of Earl Swithin and the arranged betrothed of Margery Fitzgerald. A participant in the local elite's power struggles, he relies on his family's noble status and expects obedience, serving as a significant obstacle to Margery's happiness.

Carlos is a Spanish relative of the Willard family who operates a forge in Seville. He faces discrimination from locals due to his English heritage and struggles against aggressive competitors, relying on his skilled iron-maker, Ebrima, to refine his production techniques.

Isabelle is Sylvie's mother and the wife of a Parisian bookseller. She is deeply protective of her daughter, prioritizing Sylvie's safety and happiness even above their shared dedication to the perilous Protestant cause in a fiercely Catholic city.

Cecil is a primary advisor to Princess Elizabeth. Cautious and strategic, he heavily vets anyone seeking to join Elizabeth's cause, ensuring that her inner circle is prepared to defend her against the constant threats of Catholic political maneuvering.

Also known as Scarface, the Duke is a powerful, ruthless Catholic noble in France. Along with his brother, he orchestrates violent suppressions of Protestant gatherings and utilizes spies to consolidate his family's immense power over the French crown.