Red is a teenager traveling with her friends for spring break. Carrying the heavy trauma of her mother's death five years prior, she frequently struggles with memory, focus, and guilt. Having faced significant economic hardship, she often feels isolated from her more privileged peers. She possesses strong observational skills and a deep loyalty to her friends, noticing subtle details like a red dot on the RV before the others do.

Oliver is Maddy's older brother and a pre-law college student acting as a chaperone for the spring break trip. Ambitious and highly image-conscious, he aspires to a prestigious legal career following in his mother's footsteps. He quickly positions himself as the leader of the group when the RV breaks down, though his leadership style is highly authoritarian, demanding, and self-centered.

Maddy is Red's best friend and Oliver's younger sister. Coming from a wealthy and influential family, her organized and stable life contrasts with Red's constant struggles. She acts highly protective of Red, particularly regarding sensitive topics like Red's mother, while remaining deeply tied to her family's expectations and her brother's directives.

Reyna is a Mexican American pre-med student and Oliver's girlfriend of a couple of years. She functions as a slight outsider within the established friend group. She tries to manage Oliver's demanding personality and keep the peace inside the vehicle, but she connects quietly with Red over their shared experiences outside the Lavoys' wealthy social sphere.

Arthur is the newest addition to the friend group, having met the others through Simon. He experiences severe claustrophobia, making the confines of the RV particularly uncomfortable for him. Despite his recent arrival, he pays close attention to Red's emotional needs and offers a gentle presence that contrasts with the louder personalities trapped in the vehicle.

Simon is an Asian American teenager who helped secure the RV for the trip through his uncle. Known for his carefree, humorous, and irreverent persona, he drinks tequila early in the trip and frequently clashes with Oliver's strict need for control. He aspires to study theater, though he knows he will need to fund it himself.

Catherine is Oliver and Maddy's mother and an assistant district attorney in Philadelphia. She is currently prosecuting a major, high-profile case against a prominent organized crime figure. Her career casts a long shadow over her children, particularly Oliver, who feels desperate to protect her reputation and further her success.

Grace is Red's late mother, a former police captain who died violently five years prior to the events of the novel. Her death deeply traumatized Red, particularly because their final interaction involved a harsh argument over the phone. Her memory constantly occupies Red's thoughts.

Don is an older man returning home from visiting his daughter's new baby. Helpful and well-intentioned, he approaches the disabled RV with his wife to offer assistance, completely unaware of the deadly hostage situation actively unfolding.

Joyce is an older woman traveling home with her husband, Don. Friendly and grandmotherly, she waves at the teenagers inside the RV, oblivious to the fact that their sudden arrival places them in the direct line of fire.