"With Tikhon" is the chapter in which Stavrogin takes to a retired bishop, in a monastery in town, the written confession of a crime he committed in Petersburg against a girl, and which he intends to print and distribute. It was suppressed because the editor of the Russian Messenger, the magazine serializing the novel, rejected it as too realistic; the text only came to light in 1922.
Dostoevsky tried to rework it several times without departing from its essentials. He wanted the chapter right after Chapter VIII of the Second Part, on the same morning as the scenes that follow. Since it was left out of the magazine, editions usually print it as an appendix, at the end, and the reader can read it there or in the middle. In the intended place, it changes what comes after: Stavrogin has just heard from Pyotr the plan to make him Ivan Tsarevich, a chief who hides, and the next morning he hands Tikhon the opposite, a confession made to be seen by everyone.
The conversation is a duel of frankness. Tikhon reads for an hour, says there is no greater crime, but points to a flaw of tone: it is as if Stavrogin wanted, on purpose, to show himself rougher than his heart would wish. He names the risk Stavrogin did not measure, the laughter of readers, proposes in place of publication a long, secret obedience, and, faced with refusal, predicts that he will commit another crime rather than confess. When Stavrogin says he wishes to be forgiven by a few and hated by all, Tikhon replies that there is no such thing as an isolated sin.
The chapter deals with the abuse of a girl; here it is enough to know that. What matters for understanding the book is Tikhon's judgment. Without it, the central character of the novel has no depth.