You’re sitting in a bar in Amsterdam’s red-light district some time shortly after WWII, when a man introduces himself to you. His name is Jean-Baptiste Clamence. He used to be a lawyer, and he’s now a judge-penitent. You don’t know what that is, but he promises he’ll explain it to you. He narrates in the first person, explaining that you are both from Paris, you’re both in your forties, and you’re both men. Through his monologue, Jean-Baptiste spends some time describing Amsterdam, which he believes resembles Dante’s depiction of hell (Shmoop on with Dante's Inferno). Before you part for the night, you make plans to meet at the same bar – called Mexico City – the next night.
Over your next few meetings, Jean-Baptiste fills you in on his personal history. In particular he highlights his glory days back in Paris. He used to be The Man. He was rich, successful, attractive, charming, and had good luck with the ladies. As a lawyer, he would nobly defend widows and orphans, speaking with majesty of "justice" and always believing he was in the right. He used to enjoy helping the blind cross the street, as it made him feel above everyone else. That’s just his nature, he says; he likes to physically dwell above other people.
Things continued on this way until one night, while crossing a bridge over the Seine river in Paris, Jean-Baptiste heard the sound of laughter, seemingly coming from the water below, though he could see nothing under the bridge. This spooked him considerably, and drastically changed his life. He started to realize that everything he did was duplicitous, that he was living a lie. If he helped the blind, it was only to make himself feel good. If he pretended to be humble, it was only so that he could stroke his own ego. He suddenly knew that he was a hypocrite in the worst way.
After this, Jean-Baptiste experienced a "period of discovery." Many memories he had previously repressed or forgotten came flooding back to him, all revealing his fundamental hypocrisy. One memory in particular returned, of a night when, crossing a bridge over the Seine River, Jean-Baptiste passed a woman and then heard her fall into the water below. Rather than turn around to save her, Jean-Baptiste did nothing at all. He didn’t want to risk his own hide. It soon becomes clear that this one event was the real kicker for Jean-Baptiste. He’s never been able to get over the fact that he let this poor woman drown.
Once he realized his own hypocrisy, Jean-Baptiste suddenly feared that everyone else in his life could see the same flaws. He lived in constant fear of being judged by others, and went through a variety of failed solutions in trying to avoid this judgment. Finally, he ended up in Amsterdam, practicing the profession of a judge-penitent.
By this point in the novel, you’re meeting with Jean-Baptiste for the final time, in his house in Amsterdam. He tells you his big theory of the judge-penitent. He’s been practicing his profession all this time. His job is to confess his own sins so that he has the right to judge you. In fact, his "confession" isn’t just his story – it’s yours. He’s been carefully weaving together details from YOUR life so that the portrait he’s made is a mirror he can hold up to you. It is of every man, and of no man in particular. Now, he says, begin your own confession.