Grady is a 40-year-old author whose life and career derail after his wife disappears. Unable to sleep or write for a year, he accepts an offer to stay at an isolated cabin on the Scottish Isle of Amberly to restart his career. He is heavily reliant on alcohol and struggles to differentiate between reality and his own imagination.

Abby is a journalist and Grady's wife, who vanishes on a cliff road on the night of his major book deal. Her perspective is shown through flashbacks to a therapy session a week before she disappeared, where she expresses feelings of isolation in her marriage. She is independent, career-driven, and highly observant.

Kitty is a successful London literary agent who represents Grady. She is also Abby's godmother and the person who initially connected the couple. Pragmatic and protective, she offers Grady the use of an inherited writing cabin in the Scottish Highlands to help him overcome his creative block.

Sandy is the ferrywoman and local sheriff for the Isle of Amberly. She helps Grady adjust to the island upon his arrival, providing him with transportation, maps, and an introduction to the eccentric local community. She carries a quiet sorrow related to her past.

Cora owns and operates Christie's Corner Shop on the Isle of Amberly. She provides Grady with groceries, handles his outgoing mail, and gives him bog myrtle tea to treat his insomnia. Like many islanders, she is highly protective of the community's privacy.

Charles is a late, famous author who spent his time living and writing on the Isle of Amberly. Though deceased before the novel begins, his presence lingers over the island and his abandoned cabin. He left behind an unpublished manuscript that Grady discovers under the floorboards.

Travers is a resident of the isolated Isle of Amberly. She lives a quiet life on the island and is highly protective of her family, including her baby daughter, Holly. Her presence complicates Grady's understanding of the island's inhabitants.

Midge is Sandy's sister and a lifelong resident of the Isle of Amberly. She shares a home with Sandy and helps introduce Grady to the quirks of island life, casually mentioning unsettling local crimes that unnerve the visiting author.

Arabella is one of the owners of the Stumble Inn on the Isle of Amberly. She serves Grady drinks and casually shares local gossip, including details about the properties of bog myrtle tea and the tight-knit relationships between the island's older residents.

Reverend Melody oversees the small local church and cemetery on the Isle of Amberly. She provides Grady with historical context about the church grounds and local landmarks like the Orphans Footpath.

Columbo is Grady's loyal pet dog. After Abby's disappearance, Columbo becomes Grady's sole constant companion, traveling with him from London to the isolated cabin on the Isle of Amberly.