After "diploma doctor" Denver Holt rescues "granny medicine" doctor Katie Shelton from the cellar of her burning shack on the Dakota Territory prairie, he asks her to marry him. Though Denver loves her, Katie thinks he wants merely a marriage of convenience. Worrying about the dark and difficult "tomorrows" such an arrangement would bring, she struggles over whether or not to accept his proposal. She doesn’t want to prolong the unwilling alliance she has had with him as they have worked together to heal sick settlers. Too often his "diploma doctor" methods have conflicted with her "granny medicine" ways. But as soon as Katie realizes that the marriage would benefit her sick widower father, as well as Denver’s motherless daughter Ivy whom Katie loves, Katie decides to ignore her fears--at least long enough to marry the doctor. Not until Katie and Denver overcome many near-catastrophes does she realize that theirs is not a "marriage of convenience," but a marriage of love--a mutual love between the two of them. Still, she worries about their "tomorrows."