An intelligent, beautiful young woman named Carol Milford finishes college with dreams of changing the world. She starts work as a librarian before marrying a rural doctor named Will Kennicott. She moves to his hometown of Gopher Prairie with visions of transforming the town into a rural utopia… but she's only there for one day before she realizes she might have made a huge mistake.
Carol tries her best to express her progressive political views and to get the people of Gopher Prairie to care about culture. She asks the folks of the town why they don't treat the farmers and laborers better, but nobody wants to hear about her kooky "socialist" ideas.
Then Carol tries to start a drama club so that she can put on classy plays for the town. But—surprise, surprise—the people in the club end up picking a lame play, and they totally butcher it with horrible acting. Now you might think that would be bad enough, but the worst part is that everyone in the town thinks that the play is a huge success. That's when Carol truly realizes that her efforts are for nothing.
When she gets fed up with the phony middle-class people of Gopher Prairie, Carol turns to Miles Bjornstam for companionship. Miles is the town crank—he's a man who believes in workers' rights. Carol feels like he's the only person she can be real with, but even Miles settles down once he gets married to Carol's maid, Bea Sorenson. Miles curbs his radical opinions so that his wife and son won't get bullied.
In time, Miles's wife and son die from typhoid fever, and Miles leaves Gopher Prairie feeling heartbroken. When he leaves, Carol feels like she's losing her only outlet for her deepest feelings.
With Miles gone, Carol tries as hard as she can to love Gopher Prairie and her husband Will. At first, the strategy actually works, but soon enough, Carol can feel her dissatisfaction coming back. She's just not ready to settle down into the boring mediocrity of Gopher Prairie. The problem is that Gopher Prairie isn't ready to change, so she's found herself a standstill.
When she no longer feels love for her husband, Carol tries to find an outlet for her dissatisfaction by striking up a romantic relationship with a young tailor's assistant named Erik Valbourg. Erik has big dreams, just like Carol. But Carol's husband Will finds out about the affair, and Erik leaves Gopher Prairie in disgrace. After the fact, Carol is devastated to realize that Erik doesn't have the talent to fulfill any of his big dreams. She can't help but think the same is true for her.
Worse yet, Carol learns that her frenemy Vida Sherwin has secretly been accomplishing the things she wants—like building a new school in the town—behind Carol's back. The truth is that things can change in Gopher Prairie—but they won't change just because Carol wants them do.
To save her marriage, Carol takes a trip to California with her husband Will. But the trip can't change the fact that they are two different people with very different priorities. Carol eventually gets so fed up with Gopher Prairie that she takes her son Hugh and leaves her husband Will to go live and work in Washington, D.C. She finally feels as though she's making a life for herself, but after two years, she realizes that she has exhausted almost all her possibilities in D.C.
Carol travels back to Gopher Prairie to be with her husband again. She's still not satisfied, and her only hope is that the world will provide better opportunities for her daughter.