This is a beautiful book. It is set in the Second Century, during the transition time between the death of Emperor Trajan (117 CE) and the take over of Hadrian. The hero, Gaius Petreius Ruso, a doctor in the Roman Legions, decided to transfer from his North African post (considered easy duty except for the scorpions) to the XX Legion in Britannia, cold, wet, and populated by uncivilized barbarians. At least the army had killed off the Druids.
Ruth Downie writes with great wit as we watch Ruso stumble into and out of one disaster after another.
Yes, it is a mystery. The opening line establishes that detail. Someone had washed the mud off the body. Even in his sleep-deprived state Russo discovers that the young woman died of strangulation. He turns the case over to the proper authorities who allow the investigation of the death of a local to lapse. Ruso could not let it go. He continued to ask questions, even after attempts were made on his life.
Did I mention he bought a slave girl?