Ruth Downie takes her "Medicus" series to a new level of complexity and intrigue with "Caveat Emptor". This fourth book in the highly entertaining series set in Roman-ruled Britain in the Second Century AD has protagonist Gaius Petreius Ruso and his now-wife Tilla back in Londinium after a long visit to his family home in southern Gaul. Ruso, no longer an army medic, is looking for work and reluctantly accepts an assignment from the Procurator of the province to investigate the disappearance of a tax collector and a substantial amount of tax revenue from the nearby town of Verulamium (modern St. Albans). With Tilla and the missing tax collector's wife and child in tow, Ruso moves his investigation to Verulamium, to all appearances a very law-abiding and largely Romanized settlement where the local Britons talk with Babbit-like pride about their town and province. The town fathers are not happy about the possibility of criminal scandal that has come with Ruso the Investigator, and as the bodies of the tax collector and his brother turn up, civic hostility becomes increasingly dangerous for Ruso and his family and colleagues.
Author Downie has crafted a very clever plot that is slowly revealed through Ruso's investigation in classic police procedural fashion albeit in the historic context in which the mystery is set. The conclusion is never predictable and is revealed only in the last few pages of the book.
While the plot is clever and skillfully spun out, what I liked even more about "Caveat Emptor" was the growing complexity of the characters. The relationship between Ruso and his Briton wife Tilla is extremely complicated. To be sure, there are masculine/feminine differences at work, but this is also a pairing of two extremely different people, coming from two very different cultures (cosmopolitan vs. tribal). The two are shown to be strongly committed to each other, but they are rarely in agreement about anything--their lives together, relationships with others, how to investigate a crime, etc. That personal tension is consistently written into the entire run of the story and, for the most part, strengthens it and brings a sense of historic reality to the tale.
I also thought that Downie provided a good balance of mystery story vs. historic detail in "Caveat Emptor". The plot had a modern feel to it, with its emphasis on human relationships, greed, petty power struggles, and bureaucratic bad behavior. But there is enough historic material here--living conditions, Roman medicine, transportation, burial rites, tribal relationships, etc.--to make the story original and entertaining for the reader who chooses this genre for those qualities.
A very fine book in a good series that gets more interesting with each successive episode. Recommended.