Livia is a forensic pathology fellow driven by the unresolved disappearance of her sister, Nicole. She channels her grief and guilt over missing Nicole's final phone call into a meticulous dedication to examining deceased individuals. She struggles to balance her professional medical duties with her intense personal drive to find answers about her sister.

Nicole is Livia's younger sister, a high school student with a rebellious streak and a fascination with the macabre. Deeply affected by the childhood abduction of her cousin Julie, Nicole adopts a dark aesthetic and engages in risky behaviors. She masks her underlying emotional pain with a confrontational attitude toward authority figures and peers.

Megan is a former high school overachiever who becomes a national media sensation after surviving a two-week abduction. Pressured into publishing a memoir about her experience, she outwardly performs the role of a healing survivor to comfort her parents. Internally, she battles post-traumatic stress and fragmented memories while attempting to recall the physical details of her captivity.

Terry is the local chief of police in Emerson Bay and Megan's father. He presents himself as a protective and supportive parent who is deeply invested in Megan's recovery and future prospects. He encourages her to stay close to home for college and attempts to shield her from the ongoing stress of criminal investigations.

Casey is an estranged, solitary young man whose body Livia examines early in her fellowship. Through past timelines, he is shown as Nicole's secretive, older boyfriend who shares her dark fascinations. He frequently communicates with her through online chat rooms, creating a bond based on their mutual family traumas.

Jessica is one of Nicole's closest friends. She grows increasingly concerned about Nicole's secretive and erratic behavior during the summer. Later, she provides Livia with crucial context regarding Nicole's social life and romantic interests just before her disappearance.

Rachel is part of Nicole's close-knit friend group. She observes Nicole's sudden shift away from their usual high school activities and tries to probe into her new, secretive relationship, ultimately failing to break through Nicole's defenses.

Dr. Mattingly is Megan's therapist who ghostwrites her bestselling memoir based on their sessions. He utilizes hypnotherapy techniques to help Megan retrieve fragmented auditory memories from her time in captivity, encouraging her to process her trauma safely.

Mr. Steinman is a kind, observant older man who rescues Megan and calls the authorities. He becomes a steady source of support for her, playing regular games of cribbage and encouraging her to drop the performative facade she maintains for the public and her family.

Kent is a medical examiner who trains Livia in processing field scenes. He frequently discusses his strained marriage with his high school sweetheart and mentions his desire to retreat to a solitary fishing cabin in Tinder Valley for peace and quiet.

Sanj is a medical examiner who works alongside Kent Chapple to train Livia. He offers a supportive ear to Kent regarding his marital troubles and provides professional guidance to Livia in the field.

Nate is a former handyman who worked alongside Casey. He possesses a deep, obsessive knowledge of abduction cases and shares critical theories with Livia regarding missing persons, serving as a strange but useful resource in her investigation.

Mrs. Delevan is Casey's estranged mother. The historic abduction of her eldest son destroyed her family, leaving her to cope through heavy substance use and long-term isolation.

Matt is a high school student whom Megan likes. He becomes an unwitting pawn in Nicole's antagonistic behavior toward Megan when Nicole brazenly flirts with him at summer parties.

Paxie is Nicole's aunt whose daughter, Julie, was abducted years ago. She adheres to the family's unspoken rule of never discussing the tragedy, which creates a stifling emotional environment for Nicole during family visits.

Dr. Colt is a senior pathologist who evaluates complex cases. He dismisses Livia's concerns about the suspicious holes in a victim's skull, advising her to leave investigative theories to the police force.

Dr. Larson is a neuropathology expert who works with the chief medical examiner. She attempts to help Livia identify the mysterious injuries on a homicide victim, providing specialized medical insight.