Returning to Winthrop Island after an eighteen-year absence, the thirty-six-year-old actress carries visible injuries she attributes to a car crash. In the 1951 timeline, she is an eighteen-year-old newcomer arriving for her mother's wedding, possessing a deep love for literature and an unguarded emotional nature. She struggles to fit into the island's rigid patrician society, finding herself drawn instead to the working-class locals who reside beyond the estate boundaries.

Joseph is a Portuguese American lobsterman and the son of the Fleet Rock lighthouse keeper. Educated at Brown University and highly skilled at sailing the treacherous local waters, he exists in a liminal space between the island's working-class and elite populations. In the 1969 timeline, he is a fugitive who has just escaped from prison after being convicted of a murder committed eighteen years prior.

The athletic, popular daughter of the Greyfriars estate projects an image of effortless confidence and charm. Underneath her scarlet lipstick and polished exterior, she deeply resents the polite constraints of Winthrop Island and yearns for a life outside its rigid borders. She frequently draws Miranda into her clandestine activities, manipulating those around her to protect her hidden connections and personal freedoms.

An orphaned young woman raised by her aunt and uncle, she helps run the island's general store in 1930. She is a devout, romantically idealistic seventeen-year-old who believes she is destined for something extraordinary. When she becomes deeply infatuated with a wealthy summer resident, she interprets her intense feelings as a sacred calling, unaware of the deep social divides that complicate such attachments.

A handsome, Harvard-educated heir whose family possesses newly acquired wealth and the sprawling Greyfriars estate. In 1930, he seeks to establish his place among the island's elite while privately dealing with the traumatic legacy of his abusive father. By 1951, he is a wealthy patriarch bringing a new wife into his world, though his casual exercise of class privilege sets destructive events in motion.

A woman of exquisite beauty whose early widowhood left her financially strained until her marriage to the wealthy Hugh Fisher. She brings her teenage daughter, Miranda, to Winthrop Island in 1951 for a luxurious summer wedding. By 1969, she runs Greyfriars as an artist colony to make ends meet, having been hardened by years of tragedy and public scandal.

A pragmatic World War II veteran and former pilot who returns to Winthrop Island craving a stable, ordinary domestic life. In 1951, he is engaged to Isobel Fisher but constantly worries about her restless behavior and hidden attachments. By 1969, he remains deeply entrenched in the island's social fabric, enduring ongoing personal unhappiness with stoic resignation.

The seventeen-year-old son of Francine and Hugh Fisher Sr., born shortly after the tragic events of 1951. He is emotionally open, perceptive, and eager to sail the world beyond Winthrop Island's insular borders. When his older half-sister Miranda returns in 1969, he quickly forms a bond with her and begins actively questioning the official narratives surrounding his family's past.

Hugh Fisher Sr.'s formidable first wife and a woman of impeccable social standing. Highly intelligent and largely indifferent to the prejudices of the island's culture, she eventually leaves the island's stifling atmosphere for a life in Europe. She occasionally serves as an unexpected protector for younger women finding their way through elite circles.

The keeper of the island's general store and a steadfast guardian of the local Portuguese American community. She observes the shifting dynamics between the wealthy summer residents and the working-class locals with a sharp, protective eye. Despite her community loyalty, she operates by a private code of fairness and frequently warns younger residents about the dangers of crossing strict social boundaries.

A hardworking Portuguese American fisherman and former Prohibition-era rumrunner. He later becomes the steadfast keeper of the Fleet Rock lighthouse, providing a quiet, reliable foundation for his family during the turbulent social shifts of the island.

A celebrated British film director in his sixties who discovers Miranda's acting talent and shapes her Hollywood career. He is an imposing, deeply controlling figure who demands strict obedience, casting a long shadow over his wife's personal and professional life.

The daughter of the general store owner, deeply embedded in the local working-class community. In 1969, she harbors long-standing resentment toward the wealthy summer families, actively voicing the frustrations of the island's permanent residents.

A member of the island's elite social circle who frequently monitors the behavior of her peers. She pays close attention to the indiscretions of others, using her knowledge to move through the complex social hierarchy of the patrician class.

Maria Medeiro's daughter and Bianca's cousin. Her past experiences with the island's wealthy summer residents leave her deeply affected and serve as a cautionary tale for the young women in the local Portuguese American community.

An upper-class local resident who organizes summer events and theatricals. In 1969, he invites Miranda to use her professional expertise to stage a community performance, aiming to bring some cultural levity to a tense season.

A U.S. Marshal who arrives on Winthrop Island tasked with tracking down an escaped prisoner. He attempts to manage the uncooperative, tight-knit island community while handling his more aggressive partner.

A volatile U.S. Marshal assisting in the manhunt on Winthrop Island. His aggressive approach to questioning the locals and insulting demeanor quickly create friction with the island's fiercely protective residents.