"Did Mama sing every day?" Caleb asks his sister Anna. "Every-single-day," she answers. "Papa sang, too." Their mother died the day after Caleb was born. Their house on the prairie is quiet now, and Papa doesn't sing anymore. Then Papa puts an ad in the paper, asking for a wife, and he receives a letter from one Sarah Elisabeth Wheaton, of Maine. Papa, Anna, and Caleb write back. Caleb asks if she sings. Sarah decides to come for a month. She writes Papa: I will come by train. I will wear a yellow bonnet. I am plain and tall, and Tell them I sing. Anna and Caleb wait and wonder. Will Sarah be nice? Will she like them? Will she stay?
When their father invites a mail-order bride to come live with them in their prairie home, Caleb and Anna are captivated by their new mother and hope that she will stay.