This is the book that I've chosen to use for our study of the book of Esther in our women's Sunday School class this quarter. I've read several books in preparation for teaching the class, and Inconspicuous Providence by Bryan Gregory rose to the top of the stack as the one to use as a supplement to our group study.
While many see the Bible book of Esther as being about Esther, it's really about the providence of God and how He saves the Jews from annihilation through seeming "coincidences." In addition to commentary and application of the chapters in Esther, Gregory discusses the literary techniques used by the author (who is unknown) and gives a broad overview of its historical context. Both of these aspects are necessary for an understanding of the message of the book of Esther. There are also reflection questions at the end of each chapter to further develop personal application.
The book is written on the lay level, and it's not filled with fluff. Gregory refers to scholarly research which gets us beyond the typical beautiful heroine approach to the book of Esther. Gregory has eleven pages of bibliography that those who want to go deeper and broader will find as a gold mine.
From the back of the book:
Bryan Gregory shows us how Esther's literary techniques depict God's "absent presence" and "hidden involvement," encouraging us that while God appears uninvolved, he is at work under the surface to accomplish his purposes and deliver his people--ultimately revealing his hidden presence in Christ.