Precious and Grace by Alexander McCall Smith

Mma Ramotswe and Mma Makutski find themselves busy juggling three cases, one official and two personal.  A Canadian named Susan has come to the agency to find the woman who looked after her when she lived in Botswana when she was young, and Fanwell, who works for Mma Ramotswe's husband at the automotive repair shop next to the detective agency, finds himself in possession of a stray dog that he is unable to care for. Mr. Polopetsi, meanwhile, has become involved in a pyramid scheme and has gotten several friends to invest their money.  It is up to Mma Ramotswe to extricate Mr. Polopetsi from the situation and get everyone's savings back.  As usual in this long-running series, the focus is on the interpersonal relationships of the characters rather than the mystery.