Tally is a 16-year-old who recently underwent the mandatory beautifying surgery, which altered her physical appearance to feature large eyes and clear skin while also fogging her memories. She lives a life of leisure and partying in New Pretty Town but feels an underlying anxiety and restlessness she cannot explain. Desiring to join the elite Crims social group, she is drawn to thrilling activities that momentarily clear her mind of its artificial haze.

Zane is the popular leader of the Crims, a social group dedicated to pulling pranks and chasing adrenaline. He maintains extreme facial characteristics through self-starvation and dyes his hair black with calligraphy ink to stand out from the conventional pretties. Driven by a desire to remain mentally sharp, he constantly seeks out excitement and pushes Tally to do the same.

Shay is Tally's best friend and a new pretty who recently had her eyes surgically altered to feature gemstone pupils. She sponsors Tally for membership in the Crims and encourages her to engage in the group's mischievous activities. Shay's transition to a pretty temporarily erased the trauma of her capture by Special Circumstances, though lingering resentments threaten to surface as her mind clears.

Dr. Cable is a leader of Special Circumstances, an elite and secretive branch of the city's security forces. She possesses wolf-like, cruel features with sharpened teeth and wears signature gray silks. She believes that strict control over the population is necessary to prevent humanity from repeating the destructive mistakes of the past.

David is a rebel who grew up outside the city in the original Smoke settlement. He retains his natural appearance, which includes uneven teeth and facial blemishes, setting him apart from the cosmetically altered pretties. He dedicated his life to fighting the city's control and saving individuals from the mandatory brain-altering surgery.

Andrew is a thin, wiry young man living in an isolated, primitive village in the wilderness. He serves as his community's holy man because he can speak the language of the city-dwellers, a skill he learned from his recently murdered father. He is intensely curious about Tally's world but also harbors a strong desire for vengeance against rival villages.

Peris is Tally's oldest friend from childhood. Having undergone the beautifying surgery before her, he is fully integrated into the pretty lifestyle and acts as an established member of the Crims. He values safety, comfort, and the absence of conflict that the city's interventions provide.

Fausto is an active member of the Crims social group. He possesses strong technical skills and frequently modifies hoverboards to evade the city's tracking interfaces. He is a reliable participant in Zane and Tally's schemes, though he understands the severe physical risks involved in defying the city's technology.

Croy is a young "ugly" and a member of the rebel group hiding in the wilderness. He infiltrates New Pretty Town at great personal risk to deliver a hidden package and a test for Tally. He acts as a crucial link between the city-dwelling pretties and the resistance movement operating in the ruins.

Maddy is a doctor, a founder of the original Smoke, and David's mother. She possesses deep medical knowledge regarding the city's surgical alterations and the nanotechnology used to combat them. She is highly pragmatic and prioritizes the survival of the rebel group over individual attachments.

Dex is a rebellious "ugly" who sneaks out of the city to explore the Rusty Ruins in search of the New Smoke rebels. He holds Tally in high regard for her past exploits and eagerly volunteers to act as a scout and guide for her and Zane.

Sussy is a young "ugly" who previously helped Tally during a dangerous diversion. She actively searches for signs of the rebellion and monitors unusual activity within the city's parks, providing Tally and Zane with vital information about other rebellious groups.

Dr. Anders is a trauma counselor working at the city hospital. He monitors the psychological state of the pretties, particularly those involved in accidents or exhibiting unusual behavior, acting as a subtle extension of the city's surveillance network.

Ho is a pretty and a member of the Crims who begins following Shay. He participates in dangerous rituals designed to trigger adrenaline and mental clarity, representing the extreme measures some pretties will take to break their mental conditioning.

Tachs is a pretty who joins Shay's splinter group of "Cutters." He embraces physical extremes to maintain a state of mental clarity, abandoning the safety of the city's mandated lifestyle in favor of painful rebellion.