- The novel's protagonist. Adam narrates his bike trip to Rutterburg to see his father, David. He also has conversations with someone named Brint in some kind of institution. He is a fearful, sensitive, paranoid, alienated teenager. Adam is both claustrophobic and afraid of large spaces, and his greatest fear is dogs. His favorite writer is Thomas Wolfe and he aspires to be a writer.
- Presumably a psychiatrist in an institution, although he never admits to this. In his talks with Adam, where he acts as a "guide," he is generally cold and aggressive, often pushing for specific information that does not seem relevant to Adam.
in-depth analysis of Brint.
- Adam's father. David is a respectable insurance agent in Monument. He is a good father to Adam, delighting him with worldly stories and his love of books. Adam seems constantly on edge, as if something is about to happen to him.
in-depth analysis of David Farmer.
- Adam's girlfriend. Amy is everything Adam is not—courageous and garrulous, she is not afraid of authority or of embracing her identity. She befriends Adam and enlists him to pull a "Number," a prank in the supermarket.
- Adam's mother. Louise is kind, compassionate, and protective. Adam is delighted whenever she makes him chocolate desserts. Ever since the family moved to Monument she has been withdrawn, and closes herself off in her room. She does not have friends, nor does she go to PTA meetings like other women in the community. She lives her life in fear of the "Never Knows"mdash;the state of never knowing whom to trust or what will happen next.
in-depth analysis of Louise Farmer.
- Adam's aunt on his mother's side. Martha is a cloistered nun in Maine whom Adam is not supposed to know about. Adam's mother has weekly phone calls with her.
- A fat man with a Southern accent. Arthur overlooks Hookset from his cage-like fire escape. Arnold refers to Adam as "honey" while reluctantly giving him information about his stolen bike. He is ordered around by another man inside his apartment, and is distressed that he never gets to do anything. Adam feels sorry for Arthur, whom he sees as trapped in a prison due to his obesity and his situation.
- A troublemaking teen. Whipper lives in the town of Carver who, with his two friends, harasses Adam.
Old man at gas station
- Gives Adam a map at the outset of his journey. He is paranoid about identity crimes and lack of privacy.
- Find Adam unconscious in a ditch. Arnold and Edna give Adam a ride to Hookset. Arnold is concerned about Adam's health, but Edna is paranoid and afraid of strangers.
- Steals Adam's bike. Junior Varney is immature and a known town thief. He is member of the large Varney family, and has some kind of conflict with his mother.
- Mysterious and male. Each time Adam tries to call Amy, he always seems to connect through the same operator.
Warning: If you have not finished the book, the following characters may give away some of the plot:
- David Farmer's real name and Adam's Farmer's father. Anthony was a political reporter in the town of Blount, New York, and testified against a powerful organization. After several murder attempts, he was forced to change identities and relocate with his family.
in-depth analysis of Anthony Delmonte.
- A mysterious figure that pretends to assist the Farmers. Grey is the head of a new government department called the Witness Re-establishment Program. This program assigns the Delmonte family a new identity. Grey is a secretive figure who blends into the background, and he has uncertain intentions. Grey checks up on the family a few times each month, but Adam's father believes it is to see if David is withholding any important information.
- A kindly doctor. Dr. Dupont oversees the mental hospital Adam, where he is a patient.