Darby is a college sophomore who embarks on a dangerous drive home after learning her mother has late-stage pancreatic cancer. Stranded at a remote mountain rest stop, she discovers a child locked in a van in the parking lot. She carries heavy guilt over her past rebellious behavior and strained family relationships. Her sharp observation skills are put to the test as she attempts to identify the kidnapper among the strangers trapped inside the building with her.

Ashley is a charismatic man in his twenties waiting out the blizzard at the Wanashono rest stop. He tries to keep the mood light by performing card tricks, joking about his traditionally feminine name, and initiating icebreaker games. Darby views his approachable demeanor as a welcome contrast to the other travelers, leading her to consider him as a potential ally in her plan to rescue the kidnapped child.

Larson is a nervous and unsettling man trapped at the rest stop. Darby mentally nicknames him "Rodent Face" due to his flat expression and invasive personal space. Because his demeanor immediately raises her suspicions, Darby focuses her attention on him, trying to link him to the gray van parked outside and the child trapped within it.

Jaime is a nine-year-old girl who has been abducted and imprisoned in a dog kennel inside a van outside the rest stop. She lacks proper winter clothing and is injured, forced to endure freezing temperatures while her captor waits out the storm inside the building. Her discovery sets Darby's rescue attempts in motion.

Ed is a middle-aged former veterinarian stranded at the rest stop. He carries deep regrets regarding his past struggles with alcohol misuse, which have severely damaged his relationship with his children. He provides a quiet, older presence among the anxious group of travelers waiting for the roads to clear.

Sandi is Ed's cousin and travel companion. She spends her time at the rest stop quietly reading and resting, appearing detached from the mounting tension in the room. Her presence adds to the puzzle Darby attempts to solve as she matches cars in the parking lot to the people inside the building.

Maya is Darby's mother, living in Provo, Utah. She has recently received a diagnosis of late-stage pancreatic cancer, prompting her daughter to brave severe weather to reach her. Her past relationship with Darby was fraught with arguments, leaving a legacy of guilt that drives Darby's current actions.