Jacob, the hero of the book, is a resident of Josefov, a Jewish town in Poland. After the Khmelnytsky massacres, in which his wife and three children were murdered by Cossacks, Jacob is sold as a slave to gentile peasants. During his years of slavery, he strives to maintain his Judaism by observing as many Jewish rituals as possible and by maintaining high ethical standards for himself.
While in captivity, Jacob falls in love with his master's daughter, Wanda. While Jewish law and custom forbids Jews from even touching a woman a man is not married to and also forbids Jews from cohabiting with gentiles, Jacob's love for Wanda is too powerful to overcome and they have sex. Later, Jews from Josefov come to ransom him by paying off Wanda's father and he returns to Josefov. While in Josefov, Jacob dreams of Wanda. In his dream, Wanda is pregnant and asks Jacob why he abandoned her and left the child in her womb to be raised by gentiles. Jacob decides to return to the gentile village, take Wanda as his wife, and help her convert to Judaism. Jacob and Wanda reach another town, Pilitz, where Jacob begins to make his living as a teacher. In Pilitz, Wanda becomes known as 'Sarah' and Jacob instructs her to be pretend that she is deaf and mute so as not to reveal her gentile origins. Sarah thirsts for knowledge about Judaism and at night, Jacob teaches her Jewish beliefs and practices. She suffers in silence as the women of the town gossip about her right in front of her, as they believe she is deaf and cannot hear them. Her secret is finally discovered when she screams loudly during the birth of her and Jacob's son. Sarah dies during the difficult birth, and is given a "donkey's burial" outside of the Jewish cemetery.
Jacob names his baby son Benjamin (he likens himself to the biblical Jacob whose wife, Rachel, died giving birth to biblical Benjamin); he travels to the Land of Israel with the infant, and Benjamin grows up to become a lecturer in a yeshiva in Jerusalem.
20 years later, Jacob returns to Pilitz and discovers that the town had grown and that, with it, the cemetery had grown so much that the place where Sarah was buried is now within the bounds of the cemetery. The place where Sarah was buried is not prominently marked and is unknown to the Jews of Pilitz. Jacob is old and weak and dies during his visit to Pilitz. By coincidence (or perhaps, by way of a miracle), as a grave is being dug for him, the bones of Sarah are found. The townspeople decide to bury them together, side by side.