College professor Paul Ward has invented a refrigeration unit to replace ice boxes, but has his idea stolen by another. Embittered, he sinks into discouragement. Hannah, the most mysterious housekeeper this side of Mary Poppins, talks him into losing his bitterness by privately and in-person forgiving his enemy. About the time he hits near bottom, Paul does so and the ensuing freedom and renewed energy has him starting over perfecting an even more advanced unit, and being available as a husband and father as never before.
Similar experiences occur for the other members of the family, as each turns to Hannah and learns for themselves that the turning point in their life requires this "private courage" to set them free for further glory. At the book's end, when Hannah is asked to go through what seems more than humanly possible, all the ones she has helped before gather to cheer her towards the story's culminating act of "Private Courage".