After quite a push last night in reading, I finished Persona Non Grata, a mystery set in the Roman Empire (specifically Gaul) written by Ruth Downie. The protagonist is a medical officer from the 20th Roman Legion on leave with his family when a man dies in their home from poison, and thereafter Gaius has to prove that they didn't do it. Pretty good work. It's the third book of the series, which IIRC presently is five books long.