The House of Unexpected Sisters by Alexander McCall Smith

When Mr. Polopetsi, a part-time employee of the No. 1 Ladies Detective Agency, hears about a woman named Charity Mompoloki, whom he believes was wrongly fired from an office furniture store, he asks if both Mma Ramotswe and Mma Makutsi will help him get her job back. So, the agency goes about finding out about the owner of the store, the other employees, and Charity herself to find the truth about what actually happened. On a more personal note, Mma Ramotswe gets news that her ex-husband, Note Mokoti, who treated her very badly, is back in town.  She also discovers that there is a woman named Mingie Ramotswe who lives in Lobatse. Mma Ramotswe thought that she knew everyone with the last name Ramotswe who lives in Botswana--can Mingie possibly be a relative? Regular readers of this long-running series will enjoy another visit with Mma Ramotswe and friends.