Demons is about how respectable, well-meaning people, without realizing it, open the way for a small group of fanatics. The book does not ask whether the conspirators will succeed in their revolution; it asks what, in the town, allows them to act.
The first answer is a filiation. Old Stepan Trofimovich, the idealistic liberal of the 1840s, spent twenty years in civic pose, on an allowance, and in a hysterical friendship with Varvara Petrovna, and he is the father of two sons: he educated Nikolai Stavrogin and fathered Pyotr Stepanovich, who organizes murders. The chronicler sums up that world in one phrase: the liberal "with no aim at all," the one whose fervor is spent in conversation, is possible only in Russia. That is why the novel opens slowly, like a comedy of manners, and not like a political thriller.
The second answer is the mechanism. The group does not win by force: it wins because the town does not want to appear backward. The governor yields to the logic of his own liberalism, the salon absolves Stavrogin on the strength of a remark by the governor's wife, the audience at the literary matinée discovers that it can answer back, and what binds the quintet together, Pyotr says, is the shame of having an opinion of one's own.
At the center is Stavrogin, whom each of them competes for: Kirillov and Shatov take seriously the ideas they received from him, and Pyotr invented him to make of him a chief who conceals himself. When the disaster comes, no one decided alone, and the responsibility is spread in such a way that it does not fit in a single name.