Demons tells how, in a small Russian provincial town, a small and badly organized revolutionary group, led by Pyotr Stepanovich Verkhovensky, produces within a few weeks a fire, several deaths, a murder, and two suicides, with the help of a respectable society that does not want to seem backward.
In the First Part, a chronicler, a resident of the town, paints a portrait of the old liberal Stepan Trofimovich, supported for twenty years by Varvara Petrovna Stavrogina, and introduces her son Nikolai, who drags an old man by the nose at the club and bites the governor's ear, scandals the town calls an illness. Varvara Petrovna arranges Stepan's marriage to her ward Darya; the lame woman, Marya Timofeyevna, appears; and in Varvara's drawing room, before everyone, Shatov punches Nikolai, who does not retaliate.
In the Second Part, Nikolai visits the men who received an idea from him: Kirillov, who intends to prove that he is God by killing himself, and Shatov, who believes in the people who carry God. He fights a duel with Gaganov and fires into the air. Pyotr surrounds his father, the governor, and the town, gathers his quintet at Virginsky's house, where Shigalyov reads a system that starts from unlimited freedom and ends in unlimited despotism, and proposes to Nikolai the role of Ivan Tsarevich, a chief who conceals himself.
In the Third Part, Yulia Mikhailovna's party ends in scandal and fire; the Lebyadkins are found knifed to death, and Lizaveta Nikolaevna is killed by the crowd. Pyotr leads the quintet to kill Shatov in the park, dictates to Kirillov the note that claims the crime, and takes the train. Stepan dies after reading the passage about the pigs, and Nikolai is found hanged in the attic at Skvoreshniki.