Once I read a mystery set in Roman times that was so good that I keep trying to remember who the author is so I can read more. Alas, the Roman Sleuth genre is wide enough I'll have to keep my search. Rowe, while a dedicated historian who crafts good plots, is not the master of this genre.
This novel isn't terrible; it has some strengths. For one, it's set in Roman times, but in England, so that's unusual. The characters are a mixture of Roman citizens and slaves, and the native Celts.
The main character, Libertus, has apparently been around for a few books, as the first scene deals with the manumission and adoption of his former slave/son Junio. If I'd been with him for the previous books, I'd doubtless love to hear of this new plot development with beloved characters, but as it was, the ceremonies just set the scene for the gruesome murder that threatens to curse their new dwelling.
The mystery itself is complex enough to intrigue even veteran-mystery readers, though Liberus' reason for investigating is quite contrived. They say they want to find the owner of the body so that they can placate its ghost before the festival of the Lemures (the wandering dead.) They eventually give the corpse a funeral to set the shade to rest even before Liberus discovers who it is (meaning that the investigation has no point) but Liberus investigates anyway, because otherwise there wouldn't be a mystery. He interviews slaves, inspects bodies, and otherwise does all the smart sleuthy things needed to let the reader know what nefarious deeds were afoot. That part I liked.
The strength, and the weakness of this novel is in its research. Rowe seems confident enough in this milieu that I trusted her to get the details right. I just didn't care as much about the details as she did. I growled in frustration every time she interrupted the storyline to tell us of some aspect of the culture not pertinent to the plot. I found it clumsily done, too. She has Liberus tell of us aspects of the culture in his internal voice that should have been relayed in dialogue with other characters, and she has the characters discuss other aspects of the culture that could merely have been shown through their actions.
In one scene, for example, the house slave tells Liberius,
"...You'll find a bowl of water and a special pot of altar ashes in the servants' ante-room. You are to rinse your hands and face and mark your forehead before you join the family. This is formally a house of mourning now."
Surely, someone who had been raised in this culture would have known of this ritual? And later on the same page, Liberius performs this ritual. Why not just have the slave say, "this is a house of mourning now," and have Liberius do the ritual? A unique culture is nice, but I wanted a mystery, not a textbook.
Another thing Rowe does with the exposition is say, things to the effect of "but women would not be invited to join in, as women did not have the same rights as men." Rowe does this in at least three places in the novel. This does two things for me, as a reader. One, it interrupts the story with a bizarre non-sequitur thought for a pavement-maker to have. A Roman citizen living in AD 189 has not heard of suffragettes, and it would not occur to him that women would have the same rights of men, so it felt out of place for him to comment on it.
The second thing that these asides did for me was remind me of what a shitty, shitty time women have had throughout--well, pretty much all of human history, but especially before 1990. (But she only does this for women. Slaves in this novel seem to have an Uncle Tom-like complacency with their fate.) When I read a novel--any novel--set in a time not my own, I imagine I am there. Having the cruelties of the time and place re-framed with a modern sensibility took out some of the adventure and replaced it with unfocused anger. It was as if I were reading a Regency romance and the narrator pointed out every other chapter "Of course Miss Lucy would never have the same civil rights as her feckless brother, and in fact, she was considered incompetent to give testimony at court. If, for example, her dashing suitor Count Girard were to rape her at the party, the courts would place the blame squarely upon her." We wouldn't need to know this in order to get the gist of the story. All it does is raise my feminist ire and make what was otherwise a fun story unnecessarily dark.
I prefer historical fiction if they frame the gross injustices visited upon members of society within the framework of that society, and do not compare it with my own. This all goes with having characters that are truly members of their own culture, and not ones who have modern sensibilities.
So, in short, the mystery was well done, and the setting fascinating, but the clumsy and excessive exposition got in the way of the story too often to take it from the "merely okay" to the "quite good" category.