The protagonist is Guys, a young boy from a poor family, who is caught stealing candy from a store in Paris. However, after being railroaded by a city detective named Guildias, Guys finds himself accused, convicted, and sentenced to life imprisonment for the murder of a man he never met. From that point on, most of Enzai takes place inside a dark, claustrophobic, dirty prison, where Guys experiences humiliation and torture of various kinds, much of it involving sexual acts such as rape and forcible sodomy.