Ted Conover is a journalist who embarks on a yearlong project of investigative journalism as a guard in New York’s prison system. Conover’s notes, which are recorded during his time as a corrections officer in Sing Sing prison, serve as the basis for Newjack. Newjack is later classified as contraband in New York state prisons due to its transparent reporting of the corrections system.

Dieter is Conover’s classmate and bunkmate during corrections officer recruit training. He is a former soldier who brings aspects of his military training into his training at the officer recruit academy. Conover develops a dislike for Dieter, who has a mutual dislike for Conover. Dieter threatens to shoot Conover in what at first seems to be a crude but joking manner; over time, Dieter verbalizes more perverse desires to cause harm towards women and animals. Conover is eventually assigned a different roommate, much to his relief.

Officer Smith, who is described by Conover as the “Black Mr. Clean,” is an officer who lives in Harlem and moonlights as a dry cleaner. Smith is in charge of a handpicked gallery, which is half the size of most. Conover believes that Smith succeeds where other officers have not because Smith views inmates as human beings and also maintains a sense of humor.