Lisa is a 39-year-old former nurse turned bestselling thriller author who lives on an isolated property outside her hometown of Thief River Falls. She carries immense trauma following the tragic deaths of her parents, her younger brothers, and her late fiancé, as well as the abrupt departure of her twin brother. Despite her grief and desire for isolation, she possesses a fierce protective instinct that activates when a frightened child appears on her property.

Purdue is a blond, ten-year-old boy who arrives at Lisa's farmhouse with no memory of his real name or background. Given a placeholder name by Lisa based on a character from her novel, he is convinced he witnessed a brutal crime and that dangerous men are actively hunting him. He quickly forms a tight emotional bond with Lisa as she attempts to keep him safe from local authorities.

Denis is the long-serving county attorney of Pennington County who treats the town like his personal empire. He is an aggressive, controlling figure who harbors deep resentment toward Lisa due to her past relationship with his late son. He processes his own personal tragedies through anger and a desperate need to maintain authority over his surroundings.

Noah is Lisa's twin brother who abruptly left Thief River Falls for Fargo following the deaths of their parents and younger siblings. Growing up, he and Lisa shared an unusually close bond, often feeling a telepathic connection to one another's emotions. Unable to process the overwhelming grief of their family tragedy, he chose to run away, leaving behind only a note.

Laurel is a professional who works at the local hospital and lives on a hobby farm with her husband. She presents an unflappable calm that contrasts sharply with Lisa's bubbling anxiety. Following the string of tragedies in Lisa's life, Laurel serves as her primary emotional support and confidant.

Danny is Lisa's deceased fiancé and the son of Denis and Gillian Farrell. Breaking away from his father's strict expectations to attend law school, he chose instead to return to Thief River Falls, propose to Lisa, and train as a firefighter. His tragic death while fighting fires in California remains a significant source of grief for both Lisa and his parents.

Will is a tall, former college basketball player who now works as an FBI agent based out of the Minneapolis field office. Over a decade ago, he assisted Lisa with research for her early thriller novels and harbored a crush on her. Lisa contacts him hoping he can confidentially look into human trafficking cases in northwestern Minnesota.

Curtis is Laurel's husband who lives with her on their rural hobby farm. He owns and pilots a small private plane. When Lisa asks for an emergency flight to Minneapolis to escape danger, Curtis agrees to fly her, though his true loyalties become a point of deep suspicion.

Gillian is the wife of county attorney Denis Farrell and the mother of Danny and Fiona. Supposed to be ten years sober, she has recently relapsed into heavy drinking as a coping mechanism for her profound grief over the tragedies that have struck her children.

Deputy Garrett is a police officer in Pennington County actively searching for Purdue. He claims to be a recent transfer to the area, which explains why Lisa does not recognize him. He sports a distinctive tattoo of a white alligator on his hand, a detail that immediately alarms Lisa.

Deputy Stoll is a law enforcement officer working alongside Garrett. He helps search Lisa's property and metal shed while hunting for Purdue.

Mrs. Lancaster is a local resident who lives in a house near Lisa's property. She recognizes Lisa as a famous author and provides critical information about her husband's car and the late-night police activity in their neighborhood.

Shyla is a taxi driver with a distinctive punk aesthetic who inherited a house and a pristine 1990s-era Camaro from her uncle. Years earlier, when Lisa worked as a nurse, she helped ensure Shyla's abusive boyfriend went to prison. Grateful for this past intervention, Shyla offers Lisa shelter and access to her heavily armed garage.

Willow is a local high school student and aspiring writer who idolizes Lisa Power. She writes dark poetry and claims to have recently witnessed men burying a body in the local cemetery while she was acting out one of her poems.

Tom is the editor of the local newspaper in Thief River Falls. He has known Lisa for a long time and provides her with crucial background information regarding the murder of Fiona Farrell and the movements of her abusive ex-husband.

Liam is a muscular man of average height with pale skin, short red hair, a red beard, and scarred forearms. Purdue identifies him as the violent enforcer who tortured and killed a man near the river. He actively hunts Lisa and Purdue through the woods, armed and dangerous.

Janie is Noah Power's pregnant fiancée. She lives with him in Fargo and recognizes the deep, unspoken connection he shares with his twin sister. She actively encourages Noah to return to Thief River Falls to heal his family rift.

Fiona is Denis and Gillian Farrell's daughter. She suffered through a highly abusive marriage to Nick Loudon, which ended in a divorce and a restraining order. Lisa investigates her bloody, abandoned home looking for clues to the larger mystery.

Nick is a physically abusive man who severely injured his ex-wife Fiona, resulting in a brief jail sentence. After fleeing to Florida, he recently returned to Thief River Falls. Lisa suspects he is the man Purdue saw tortured and killed in the woods by Denis's crew.

Mrs. Reichl is the senior librarian in Thief River Falls. She has known Lisa since she issued her first library card as a young child. She connects Lisa with Willow Taylor to help her investigate strange local rumors.

Madeleine is Lisa and Noah's late mother, originally from France. Her sudden death in a car accident two years prior to the story triggered the string of devastating family tragedies that her children refer to as the Dark Star.