Darby Thorne is the protagonist and primary narrator of No Exit, though other characters have shorter narrative installments in the text. Darby begins the novel struggling with her feelings about the news that her mother has terminal pancreatic cancer. The grief she feels about this diagnosis is compounded by her difficult history with her mother, with whom she frequently argued in her high school years, as Darby often partied and misused drugs, leading to conflict between mother and daughter. The unknown deadline of her mother’s approaching death leads Darby to travel as far as she can before the snow stops her, which leads her to be stranded at the Colorado mountain rest stop where a kidnapping is taking place.

When Darby discovers that Jay is being held prisoner in the Garvers’ van, she becomes quickly determined to do something to help the little girl, though she initially doubts both her understanding of the event taking place and her ability to do anything about it. This latter fear leads her to trust Ashley, who, though he has put on a friendly and chatty front, is the more devious of the Garver brothers. When her plans begin to fall apart and she faces increasing fear, danger, and violence, Darby doesn’t falter.