Effi Briest is one of the three great novels of adultery of the 19th century, with Madame Bovary and Anna Karenina. But as I have indicated in my review of Flaubert's masterwork, the real themes in Madame Bovary are the harshness of society and the boredom of life in a small provincial town. Although Effi Briest is a totally different novel, these two themes are prominently present here as well.
Effi Briest is a very different person from Emma Bovary. She is well-educated and full of humor. Born as only child in an aristocratic family, when she is just 17, her parents marry her off to the 38 year old Baron Geert von Instetten, who of all things had been the unsuccessful suitor of the mother! This is all the more wrong as Effi is not only still a child, but also has a childish character - she should have been allowed to mature before being thrown out on marriage and society. But having become "Staatsanwalt," Instetten now has a high social position and he seems an ideal party to the parents. From Effi's side, there is of course no love, only respect.
After the marriage and a honeymoon trip to Italy where Effi is dragged from museum to museum, the couple starts living in an old house in Kessin, on the Baltic Sea, a boring small town filled with boring people. Fontane provides realistic descriptions of the dark scenery of this northern German port town. Effi is often home alone when her husband's duties keep him away and, child as she still is, she is afraid of ghosts in the drafty house (there is a legend of a mysterious Chinese). Her husband is a stiff man for whom only his career and standing in society are important. He has no ear for her silly fears. Effi suffers a nervous breakdown, but there are ups and downs, and a daughter is also born.
Then the debonair major Crampas arrives in the small town and Effi jumps at the chance of pleasant company. She likes physical exercise, and the major joins her for horse riding in the dunes. They flirt, and in a delicate way Fontane indicates that their relation has gone outside of the boundaries of normal friendship. Effi pulls back, but what has happened, cannot be undone, and she feels guilty.
Happily, there is a change of location: Instetten is promoted to a job in Berlin. Effi feels freer and happier here, the house near the Berlin Zoo is also nicer, and she loves the cosmopolitan atmosphere of the capital, but the affair with Crampas also makes her increasingly reluctant to be together with her husband as his presence makes her feel guilty. When she visits her parents, she finds pretexts to stay away as long as possible from Instetten. She also makes a long visit to a spa to take a cure for her nervous disorder.
During that absence Instetten purely by chance - for he never suspected anything - finds the love letters Effi has exchanged with Major Crampas. He explodes, his happiness is gone, his only feeling is to punish those responsible for it. He immediately travels to Kessin to fight a duel with Crampas and manages to kill him. He also divorces Effi for adultery, putting all the shame on her. Instetten gets charge of the child, for society regards Effi as a "depraved woman."
Even her parents treat her harshly: they support her financially, but do not allow her to come back to the parental home, because of the social disgrace. Nineteenth century Germany was a very strict society. A "fallen woman" was regarded as a contagious disease, nobody wanted to be near her. So Effi lives secluded in a small house in Berlin with only one trusted servant. Later, there is a meeting with her daughter, but after two years the child is completely estranged from her (something the father has taken care of), so this makes her only more unhappy. Her nervous disorder gets worse, and finally her parents relent and put their daughter above their reputation. They allow her to come back to her old home, vaguely feeling their own responsibility in the matter, without however questioning the rules of society. Finally the illness gets more serious again and Effi dies serenely. So ends the novel that shows how society with its petrified moral concepts can crush an individual life.
Theodor Fontane wrote novels that were completely different from anything written before him in Germany. His influence on 20th century authors, especially Thomas Mann (Buddenbrooks), was enormous.
Effi Briest was filmed five times - the most famous version was made in 1974 by Rainer Werner Fassbinder, with Hanna Schygulla as Effi Briest.
The German original is available at Gutenberg, while also several translated versions exist, for example in Penguin Books. This site has a detailed overview of the novel's contents.