Step Up

At seventy years old, Rose Cowden boarded a plane for her eleventh mission trip to South Africa and asked God the question that had followed her for fourteen years: How could she ever be at peace with letting this go?

It began with a single word from a pastor who told her, "I think it's time for you to step up." Rose said yes, not knowing it would carry her across a seventeen-hour flight, past every fear she owned, and into the dusty villages of Madutle, South Africa, again and again.

In Step...