Fitzgerald's first-person story is based on the diary of ten year-old Susan Parker who with her parents and twelve year-old brother Jerry traveled by wagon train from their comfortable home in St. Joseph, Missouri, to Fort Laramie, where the bookkeeper father dreams of raising livestock. The first part of the book centers on the conversion of Sue's mother, who has opposed the move, from a finicky snob to a ""real pioneer woman"" (the crisis occurs when generous but uncouth Mrs. Cleaver saves her from dying of pneumonia). From the start though there are illustrations of Jerry's courage, responsibility and general manliness -- all preparation for his climactic feat and sacrifice: first, as Sioux braves look on from a hilltop, he heroically kills a buffalo who is about to charge Mr. Cleaver, and then he saves the wagon train from Indian attack by agreeing to live with the tribe as the chief's adopted son. (Sixteen years later, an epilogue reports, Jerry is killed at Little Bighorn and his own son, now six, is presented to the Parkers.) Though much of the dialogue is stiff and repetitive, that the story is based on fact adds interest to both the details of pioneer coping and the highlights of Jerry's adventure.