The book begins with the spring after the Long Winter, and ends as Laura becomes a schoolteacher so she can help her sister, Mary, stay at the school for the blind in Vinton, Iowa.
Laura takes a job in town sewing shirts to help earn money for Mary's college education. She hates the work but never complains, and earns $1.50 per week for a total of $9.00 before the spring rush ends. The family gets a setting of chicks from their friends, Mr. and Mrs. Boast, and things are looking up. Pa plants a corn crop for cash, which is growing beautifully until blackbirds decimate the crops. The family eats the blackbirds that Pa shoots, but it's impossible to kill them all and they lose the crop. Laura thinks that Mary won't be able to go to college that year, but Pa sells a heifer and he and Ma bring Mary to college.
While Ma and Pa leave to take Mary to college, they leave Laura in charge of the house. She finds it hard to cope, especially because to distract herself and her younger sisters from their sorrow of Mary's departure, they decide to do all the fall housecleaning. It's a grueling week but they finish in time.
The family moves to town for the winter, to protect themselves in case the area has another hard winter. Laura and Carrie attend school in town and Laura is reunited with her friends Minnie Johnson and Mary Power, and meets a new girl, Ida Brown. Nellie Oleson, Laura's nemesis from Plum Creek, has moved to De Smet and is attending the school. Nellie turns the teacher, Eliza Wilder, against Laura and Miss Wilder loses control of the school for a time.
The winter is a "whirl of gaiety" with literary society meetings, parties and church socials. Laura find she is depressed, missing Mary and not wanting to study. She neglects her school work for a period of several months but spends the entire summer back on the claim, studying hard. By the next winter, she finds herself escorted home several nights in a row from church meetings and a school exhibition by the older Almanzo Wilder. On Christmas Eve, a surprise visit from the superintendent leaves her with a teaching certificate and a job 12 miles south of town.