Cadence is an 18-year-old girl living with her mother in Burlington, Vermont. She spends her summers on the private Beechwood Island with her extended family. Following an unexplained accident during her fifteenth summer, she suffers from chronic migraines and relies on strong pain medication. Her amnesia regarding the event leaves her isolated and confused. Possessing an ironic view of the world, she struggles to reconcile her idealistic values with her family's obsession with maintaining a facade of perfection.

Gat is the South Asian son of Aunt Carrie's partner, Ed. He spends his summers on Beechwood Island but frequently feels alienated by the wealthy, white Sinclair patriarch. After witnessing poverty during a trip to India, he develops a strong political awareness. He challenges the family's materialistic values and refuses to accept the social inequality he sees around him.

Penny is Cadence's mother. She strictly enforces the Sinclair family rule to appear normal at all times, refusing to acknowledge emotional pain or weakness. When her husband leaves suddenly, she demands that Cadence hide her distress. She aggressively pursues her share of the family inheritance, frequently arguing with her sisters over island property.

Harris is the imposing patriarch of the Sinclair family. He controls his children through their trust funds and uses his immense wealth to manipulate their behavior. He relishes his power, forcing his daughters to compete for houses on the island. He holds traditional, prejudiced views and expects absolute obedience from his dependents.

Mirren is Cadence's cousin and a core member of the friend group. She acts as a grounding, empathetic presence among the teenagers. She prefers to focus on kindness and emotional warmth, adopting a personal motto about treating others better than required.

Johnny is Carrie's son and the final member of the Liars. He brings a lighter, playful energy to the group, often spending his time playing games and building with Legos. Behind his easygoing exterior, he cares deeply for his cousins and serves as a supportive presence during Cadence's recovery.

Tipper is the matriarch of the Sinclair family. She functions as a socially adept companion who helps display the family's extreme wealth through her collections of fine goods, including illegal ivory statues. Her sudden death fractures the family's stability and accelerates the bitter inheritance disputes among her daughters.

Bess is one of Harris and Tipper's three daughters. She actively instigates many of the family's inheritance battles, coveting the Boston property and attempting to secure the largest houses on Beechwood Island. She is openly hostile toward outsiders, famously stating that Gat does not belong with them.

Carrie is Cadence's aunt and Johnny's mother. She balances her relationship with her South Asian partner, Ed, against her fear of losing her inheritance. She refuses his marriage proposals to protect her financial standing with her prejudiced father. She frequently wanders the island at night, burdened by unspoken emotional distress.

Taft is one of Bess's children, part of the younger generation known as the Littles. He is a sensitive child who suffers from anxieties. He frequently calls Cadence to express his fear of the wind and the purportedly haunted houses on Beechwood Island.

Will is Carrie's youngest son. He struggles with severe nightmares and relies on the older cousins for stability. His mother often ignores his night terrors when she is preoccupied with her own distress.

Liberty is one of Bess's daughters. She embodies the traditional Sinclair traits more readily than the other children. She shows an early interest in clothes and boys, working to maintain the family's standard of perfect appearances.

Bonnie is one of the Littles and Bess's daughter. Unlike the typical Sinclair, she holds a fascination with morbid subjects and the supernatural. She reads books about apparitions and bluntly compares Cadence's pale appearance to a vampire.

Ed is Aunt Carrie's partner and Gat's father. He works as an art dealer in New York. He faces quiet prejudice from the Sinclair patriarch due to his South Asian heritage. He frequently remains on the mainland, aware that his presence jeopardizes Carrie's standing with her father.