Tomasz Oletsky narrates his deposit to the prairie witch, beginning with his life in Polish Golab under German Kulturkampf. Recruited by an Agent for the Burlington and Missouri River Railroad, he and his young wife Ania emigrate to Nebraska in 1873 to escape Germanization and serfdom. On the journey, they meet Andrew Dawson, a Black porter who saves Ania from fever, but Tomasz quickly absorbs American racial hierarchies and distances himself, ashamed of his sense of relief at being placed above Black and Indigenous people.

Settling on the Loup River near the Pawnee reservation, Tomasz claims 160 acres of stolen Pawnee land. He observes the systematic dispossession of the Pawnee, parallels it to the Polish experience under Germany, yet does nothing. He endures the 1874 locust plague and prairie fires, learns of General Mitchell's coordinated arson against Indians, and steals timber from Pawnee forests. By 1876 the Pawnee are forced to Oklahoma.

In 1885, Ania works as a cook at the Genoa U.S. Indian Industrial School, where she witnesses the abuse of Native children, including a Counselor (a prairie witch) who extracts students' memories. Ania tries to help a runaway Lakota girl called Ellen reunite with her family at Rosebud, but Tomasz, fearing financial ruin, captures the sick child and returns her for a five-dollar bounty. Ania loses her faith and her fourth pregnancy.

Grieving, Ania visits the prairie witch on the Loup to deposit her horrors. The witch predicts a healthy son and gifts them a small brass harp. Ania subsequently bears Harp, Frank, and Lada. Tomasz secretly destroys Ania's deposit slips to protect her.

After the Kinkaid Act, Tomasz and thirteen others found Uz County, signing a pact excluding Black settlers. To stem land-seeker competition, Tomasz invents the rumor that the Sioux are planning an uprising. The lie spreads and leads to the murder of Donald LeBleu, a Lakota father, by Timothy Ruskin, who is acquitted. Tomasz brings this guilt, along with his mother's final letter describing Polish expulsions, to the witch as his deposit.