Aaron is a 38-year-old federal investigator working in the financial crimes unit in Melbourne. He is a solitary, taciturn man who struggles to form meaningful personal connections, a trait exacerbated by his unresolved grief over his late father. He approaches his job with intense dedication, holding a firm belief that white-collar criminals cause just as much societal destruction as violent offenders.

Carmen is a 38-year-old federal agent who recently transferred from Sydney to the financial crimes unit. Having previously worked in child protection, she moved to financial investigations to escape the emotional toll of seeing children in harmful situations. She brings a deep sense of empathy to her police work and actively fosters a candid, supportive friendship with her isolated partner.

Alice is a high-ranking executive at the boutique accounting firm Bailey Tennant. She is widely disliked by her coworkers due to her abrasive personality, frequent bullying, and ruthless corporate mentality. To save herself from prosecution, she secretly functions as a confidential informant for federal investigators looking into her company's illicit finances.

Lauren is a middle-management executive at Bailey Tennant whose work performance has recently plummeted. She suffers from severe anxiety and disordered eating, issues rooted in her own adolescence and currently triggered by the severe bullying her teenage daughter endures at school. She projects a passive exterior but harbors deep resentments.

Jill is a high-ranking executive at Bailey Tennant and the sister of the firm's CEO. Though she originally wanted to be a teacher, she bowed to family pressure to join the corporate business. She acts as the unofficial leader of the women's group during the hike, attempting to enforce order and cooperation as conditions deteriorate.

Daniel is the athletic, driven CEO of Bailey Tennant. He is the primary target of Aaron and Carmen's federal investigation into multi-generational corporate embezzlement. He runs a toxic workplace, shows little respect for his female employees, and uses his vast wealth to cover up his family's misdeeds.

Breanna, who goes by Bree, is Alice's dedicated assistant at Bailey Tennant. She is physically fit, capable in the outdoors, and highly focused on climbing the corporate ladder. She attempts to manage her boss's difficult temperament while maintaining peace among the hiking group, hoping her efforts will result in a coveted promotion.

Bethany, who goes by Beth, is Breanna's twin sister and works a low-level data entry job at the firm. She lacks the corporate ambition of her peers and has a personal history involving addiction and incarceration. These factors make her a frequent target for judgment and scapegoating within the women's hiking group, particularly from Alice.

King is a senior sergeant with the state police who leads the official missing persons case for Alice. He focuses his investigation on the harsh realities of the physical terrain and the dangerous criminal history of the Giralang Ranges, viewing the financial crimes angle as secondary to the immediate physical threat.

Margot is Alice's teenage daughter. She recently suffered a humiliating privacy violation when her ex-boyfriend circulated explicit photos of her online. Despite her victimhood in this instance, she mirrors her mother's cruel behavior by severely bullying her peers at school.

Rebecca is Lauren's teenage daughter. She stopped attending school six months prior to the events of the novel due to severe, targeted bullying regarding her weight. The harassment has left her deeply anxious and struggling with disordered eating.

Joel is Daniel's eighteen-year-old son, expected to eventually take over the family company. He recently synced a new tablet to his phone and allowed explicit images of his underage ex-girlfriend to be distributed to his friends, creating a massive legal liability that his parents are trying to suppress.

Martin Kovac is an infamous, deceased serial killer who stalked and murdered several young women in the region decades ago. The shadow of his crimes still heavily influences how the public and law enforcement view the area where the hikers vanished.

Sam is the son of the notorious serial killer Martin Kovac. He has a lengthy criminal record and is known to use the deep bush country for drug trafficking and other illegal enterprises.

Ian runs Executive Adventures, the local outfitting business contracted by Bailey Tennant to organize and supply the multi-day team-building exercises in the Giralang Ranges.

Leo is the founder of Bailey Tennant and the father of Daniel and Jill. He established the complex money-laundering operations that form the basis of the current federal investigation against his children's business.

Jaime is Carmen Cooper's fiancé. His presence in her life represents the healthy, stable personal connections that Aaron lacks and struggles to build for himself.