April is a 26-year-old former waitress who recently married Eddie Carter. Having grown up in an abusive household and lived a transient life on the run with her mother, she possesses sharp survival instincts. When an injured hitchhiker dies in their care, her impulse to flee clashes with her desire to build a stable life.

Eddie is a 27-year-old mechanic and army veteran recently returned from Iraq. He lives with post-traumatic stress disorder, which occasionally causes visual and auditory hallucinations that make him doubt his own perceptions. Quiet and observant, he is frequently underestimated by others but provides a steadying presence for April as they are drawn into a murder investigation.

Quentin is an intimidating local police detective in Coldlake Falls, easily recognized by his pristine tracksuits. He relentlessly chases suspects and is determined to close the Atticus Line cases by any means necessary. His abrasive interrogation tactics quickly put him at odds with April and Eddie.

Rose is a local bed-and-breakfast owner in Coldlake Falls who takes in April and Eddie at the direction of the police. She is a widow who faces local gossip regarding the death of her husband, Robbie. Brusque and sharply observant, she quickly assesses April and Eddie's innocence and encourages them to conduct their own investigation.

Beatrice and Gracie are teenage sisters living in Coldlake Falls who are deeply invested in the local true crime history. Beatrice is sixteen and observant, while the older Gracie leverages her community service at the police station to access official files. Resourceful and intelligent, they maintain extensive records on the regional murders.

Shannon is a woman from Midland, Michigan, who went missing in 1977. She struggled with substance use and mental health challenges but had recently committed to sobriety before her disappearance. She is the subject of a desperate search by her friend Carla.

Rhonda Jean is a young woman whom April and Eddie find badly injured on their way to Coldlake Falls. She has recently been staying at the Hunter Beach campsite after leaving an abusive home. Her severe injuries pull April and Eddie into the mysteries surrounding the town.

Beam is a local police detective who works alongside Quentin. He is cynical and often lets his partner take the lead during interrogations. While he pushes alternate theories about the crime, he occasionally shows a more empathetic side.

Kal is a uniformed police officer who grew up in Coldlake Falls. He is more approachable than the detectives and occasionally shares local knowledge with April and Eddie. He balances his official duties with his own curiosity about the town's ongoing mysteries.

Diane is April's mother, currently serving time in a California prison. She raised April on the run, teaching her how to blend in, adopt fake identities, and leave everything behind without a trace. Her survival-focused parenting left a lasting impact on April's ability to trust others.

Max is a 28-year-old local man who becomes a suspect in the ongoing police investigation. He lives on a nearby farm and struggles to remember his actions on the night of the crime, drawing intense scrutiny from law enforcement.

Gretchen is a young woman staying at the Hunter Beach campsite. She is deeply affected by the recent events surrounding Rhonda Jean and shares local rumors about the area's history with April and Eddie.

Todd is a young man staying at the Hunter Beach campsite. He is part of the transient community living there and is questioned by April and Eddie regarding the night Rhonda Jean left the camp.

Mitchell is a young man staying at the Hunter Beach campsite. He happens to be awake the night Rhonda Jean leaves the camp and provides crucial observational details to April and Eddie.

Carla is a restaurant worker in Midland who previously struggled with substance use. She formed a close bond with Shannon Haller while they were in rehab together. Dedicated to finding out what happened to her friend, she placed classified ads hoping for her return.

John Haller is a resident of Midland, Michigan, and the father of Shannon. He maintains a difficult relationship with his daughter and filed a missing persons report nearly a year after her disappearance. He lives alone in the house where Shannon grew up.

Trish is a local woman driving along Atticus Line. Though she does not usually pick up hitchhikers, she stops for April. She quickly becomes entangled in the strange occurrences on the road, exhibiting severe confusion and distress.

Robbie is Rose's deceased husband and a former police officer in Coldlake Falls. Despite being a highly capable detective, he faced persistent racism on the force that stalled his career. He is remembered by his widow for his intelligence and dedication to unsolved cases.

Katharine is a former hitchhiker who was killed on Atticus Line several years prior to the current events. Her memory is preserved through a faded cloth flower and card left near the edge of the road, marking the site of her tragedy.