Alice is a single mother of three children living in the coastal town of Ridinghouse Bay. She supports her family by creating art out of old maps and selling the pieces online. When she spots a confused man sitting in the rain on the beach, she impulsively offers him shelter in her rented shed. Despite her history of questionable decisions regarding men, she feels an instinctive trust toward the stranger.

Frank is an amnesiac man who finds himself on a beach with no memory of his identity or past. Given the name "Frank" by Alice's young daughter, he speaks with a southern accent and carries only soaked, unreadable train tickets in his pockets. He accepts Alice's offer of temporary shelter but remains deeply fearful of contacting the police, preferring to let his memories resurface naturally.

Lily is a twenty-one-year-old immigrant from Ukraine who recently relocated to England after marrying Carl. She spends her days studying accounting through a correspondence course while adjusting to her new environment. When Carl vanishes shortly after their honeymoon, she begins an urgent search for him, only to discover a series of unsettling secrets about his life.

Carl is Lily's missing husband, a financial services worker who provides a comfortable life for his young bride in Oxted. He presents himself as a devoted partner, yet his sudden disappearance leaves Lily entirely alone. The subsequent discovery of his forged passport and locked desk drawers suggests he carefully controls the information he shares about himself.

Gray is a seventeen-year-old teenager spending the summer of 1993 on the coast with his parents and sister. He is observant and generally skeptical of new people, particularly those who seem overly confident. He actively watches over his younger sister, Kirsty, stepping in when he feels she is making poor choices.

Mark is an affluent nineteen-year-old staying with his aunt at her grand estate in Ridinghouse Bay in 1993. Confident and accustomed to getting his way, he uses his upper-class background and smooth manners to impress tourists. He quickly sets his sights on Kirsty Ross, persistently courting her despite her brother's obvious disapproval.

Kirsty is Gray's fifteen-year-old sister, vacationing with her family in the summer of 1993. Beautiful and somewhat naive, she catches the attention of a wealthy older boy. Her desire to experience teenage milestones makes her susceptible to peer pressure and the flattery of older teenagers.

Kitty is Mark's wealthy aunt, who owns an impressive seaside estate complete with peacocks and an orangery in Ridinghouse Bay, as well as property in Harrogate. Eccentric and recently widowed, she hosts Mark for the summer but struggles to control his aggressive behavior.

Russ is Carl Monrose's friend and former colleague. An ordinary man with a new baby and a wife named Jo, he realizes he knows very few concrete details about Carl's life before his marriage. When Lily asks for help, Russ steps in to assist her investigation despite his family obligations.

Derry is Alice's fiercely loyal best friend in Ridinghouse Bay. Practical and protective, she frequently steps in to help Alice manage her chaotic household and navigate school issues for her children. She is immediately suspicious of the amnesiac man sleeping in Alice's shed.

Jasmine is Alice's sixteen-year-old daughter. She serves as the critical voice in the household, openly questioning her mother's impulsive decisions and pushing back against the idea of letting an unidentified man live on their property.

Kai is Alice's fourteen-year-old son. As the only boy in the household, he feels a strong need to protect his mother and sisters, making him initially hostile toward Frank. He quietly observes the changing dynamics in the home.

Romaine is Alice's six-year-old daughter. Cheerful and highly trusting, she quickly warms up to the stranger in their shed, officially dubbing him "Frank" and treating him like a welcomed guest.

Anthony is Gray and Kirsty's father. He brings his family to Ridinghouse Bay for a seaside vacation in 1993 and tries to manage the shifting dynamics as his children grow older, occasionally stepping in to set boundaries with local teenagers.

Pam is Gray and Kirsty's mother. She enjoys the family vacation in 1993 and is initially charmed by the polite manners of the wealthy boy pursuing her daughter, failing to see the warning signs her son notices.

Lesley is a brusque, sharp-witted journalist for the *Ridinghouse Gazette*. She possesses detailed knowledge of local history and past events in the coastal town, serving as a critical link to historical records.

Beverly is a police officer who takes Lily's missing persons report. She assists Lily in the early stages of the investigation into Carl's disappearance, checking databases and managing the official response.

Izzy is a local girl in Ridinghouse Bay in 1993 who hangs out with Mark Tate's social circle. She flirts with Gray at a pub and invites him to a party, drawing him into Mark's orbit.

Lily's mother lives in Ukraine and works as a translator. She checks in on her daughter and encourages her to return home after Carl goes missing, worrying about her isolation in a foreign country.

An evasive woman who speaks to Lily on her wedding day. When Lily calls the number again after Carl vanishes, the woman denies having a son and hangs up.

Hero is a Staffordshire bull terrier belonging to Alice. Left behind by a former tenant, he is a friendly dog who quickly warms up to Frank.

Griff is an elderly greyhound adopted by Alice as a puppy. Typically standoffish around strangers, her positive reaction to Frank serves as an early indicator to Alice that he is a good person.