Spaz is an epileptic teenager living in the dystopian Urb, unable to use the addictive mindprobes that occupy most of the population. Because of his "deef" (genetic defect), he was banished from his foster family and now lives in the Crypts under the control of latchboss Billy Bizmo. He works as a thief, recovering items for his boss, which eventually leads him to an unusual old man and a hidden world of written words.

Ryter is an elderly "gummy" living in a stackbox in the poorest section of Billy Bizmo's latch. Unlike the rest of the Urb's population, he retains a vast knowledge of the "backtimes" before the environmental disaster known as the Big Shake. He spends his days handwriting a physical book, placing immense value on preserving history and memory.

Lanaya is a genetically improved teenager, or "proov," living in the opulent, pristine society of Eden. She travels into the impoverished Urb with armed escorts to hand out food to the "normals." Possessing a confident and commanding presence, she has been raised to eventually assume a position of leadership among her people.

Bean is Spaz's twelve-year-old foster sister who remains in their original latch. She is highly intelligent, perceptive, and deeply compassionate. She suffers from a severe relapse of a life-threatening illness, prompting a desperate message for her brother to visit her before it is too late.

Billy Bizmo is the unpredictable and dangerous latchboss of the Crypts, commanding a gang called the Bully Bangers. He bears old, pale scars on his neck and rules his territory through intimidation and strict obedience. He explicitly forbids mixing with proovs and demands absolute loyalty from anyone living in his domain.

Little Face is a five-year-old orphan who survives by hiding in the stackboxes of the Urb. Largely mute, he communicates primarily using the word "chox," referring to the chocolate bars he receives. He proves remarkably agile and observant when crossing the dangerous ruins of the city.

Lotti Getts, also known as the White Widow or Nails, is the fierce latchboss of the territory where Spaz's foster family lives. She enforces strict bans on mindprobes and maintains control using a gang called the Vandals. She is a cunning and proud leader who views outsiders with intense suspicion.

Vida Bleek operates an underground network within Lotti Getts's latch. He commands a terrifying group of enforcers known as the Furies, who wear hooded capes and skull masks. Small in stature but highly intelligent, he constantly plots to expand his influence over the local trade markets.

Mongo the Magnificent is the fearsome latchboss of a neighboring territory, controlling a gang known as the Monkey Boys. He has spent over a year continuously connected to an endless mindprobe, a decision that leaves his territory falling into extreme poverty and chaos while his followers grow increasingly feral.

Jin is Lanaya's father, known in Eden as a "contributor" who helped raise her after genetic modification. He wears fine clothing, sports a small, dark, pointy beard, and enjoys playing chess. He raises his daughter to think independently and engage with complex problems.

Bree is Lanaya's mother and a contributor in Eden. She possesses golden hair and the flawless physical features typical of a proov. She maintains a traditional, nurturing approach to motherhood and thrives on caring for young children in her spacious home.

Charly is Spaz's former foster father. He is fiercely protective of his daughter Bean but harbors deep prejudice and fear regarding Spaz's epilepsy. His harsh reactions and ignorance ultimately lead to him forcing Spaz out of their home to protect the rest of the family unit.

Kay is Spaz and Bean's foster mother. She often defers to Charly's decisions regarding the household and their children. Though she tries to care for Bean during her illness, she maintains a passive role in the family dynamics and the initial decision to exile Spaz.

Gorm is a young Technical Security Guard (tek) acting as the second-in-command for the Monkey Boys. He struggles to maintain the fearsome reputation of his gang while dealing with the deteriorating physical and mental state of his leader.