"Mma Makutsi was unconvinced. "Where there is smoke there's fire, Mma. I have always said that." Mma Ramotswe could not let that pass. "But what does Clovis Andersen say in The Principles of Private Detection, Mma? Does he not say that you must be very careful to decide where the smoke is coming from? Smoke can drift, Mma. Those were his exact words, I think."