Louisiana Territory prairie and the flood and earthquake year of 1811 background a fair period piece of struggle, treachery, and first love in pioneer days. At New Madrid on the Mississippi river, orphaned Rosanne lives with her Uncle Ot and Aunt Martha on their farm. Through the summe, ridden with the forebodings of an ominous comet that has appeared in the sky- Rosanne comes to know Guyon, the swashbuckling boatman who, it seems, will never settle down- and wonders about the outcome of her cousin Randy, last heard of in New Orleans in the company of questionable M. Boyer. Then the earthquake floods the surrounding land. But good fortune follows bad. Randy's nemesis is reckoned with, Aunt Martha and Uncle Ot head for luck in the northwest, and Guyon, ready to take a steady job in St. Louis, offers happy Rosanne a new life.