It is Florence, 1536. Cesare Aldo is an officer of the Otto, a criminal court with its own investigators. Aldo has secrets, and Florence runs on the trading of secrets. Aldo ends up investigating the murder of a moneylender Samuele Levi, who he had recently protected as he travelled from Bologna back to Florence. Aldo only trusts one other Otto investigator, young Corporal Strocchi. Strocchi is investigating the horrendous death of the latest courtesan to show themselves off at Sunday Mass, but he discovers this courtesan is a young man, and that not many care about the death of a homosexual.

One thing both victims have in common is leaving incriminating books behind. In Levi’s case it is his ledger, written in Hebrew, which at this time is a language only used for liturgy and intra-Jewish commerce, making it hard for Aldo to find out why it has been stolen. And the young courtesan, Corsini, left behind a diary in which he described many of his high-profile clients, complete with drawings – and when Aldo hears that a despicable Otto officer, Cerchi, has Corsini’s diary, he joins the many Florentines who are nervous of their future.

As both investigations proceed, it becomes apparent that there is more than just greed and fear behind the crimes – there is the threat of insurrection. A plot threatening the Duke of Florence, Alessandro. And Aldo is given a deadline – he must solve the case in four days, or the case will be taken from the Otto and handed over to the military. If the Duke is killed, a power vacuum will result. And one of the many willing to fill the vacuum is Cosimo I de’Medici, son of Aldo’s former boss, Giovanni and his widow, Maria, a staunch supporter of her son’s cause.

City of Vengeance is full of secret alliances and untrustworthy characters. Many Florentines are of no importance, most of them women; mothers and widows with “all the responsibilities and none of the power”, or young women mostly dependent on their fathers or future husbands. Then there are the men who don’t conform and who must love in secret and live under constant threat. And those in the Jewish community, with their own laws, tolerated due to their facility with money, but when murder is involved the law of Florence takes precedence.

And the law of Florence is not as just as one might think, employing torture and bribery, and dealing in secrets. Florentine society is a hierarchy, from its highest echelons down to its dreaded prison, Le Stinche. It is a mercenary, pragmatic society and the streets of Florence are awash in butchers’ blood, mud, and shit. Yet Aldo “loved Florence, though that love had often got unrequited thanks to the city’s laws, and sometimes its people.” And when human blood starts running in the streets, he wants to do the right thing, for the victims not for the rulers: “Did it matter who led Florence? One ruler was little different from the next”.

There are some complex characters in City of Vengeance: Aldo, committed, horrified to realise that people are dying because they were helping him with his enquiries, constantly being beaten up and staggering on through pain and exhaustion; Rebecca, Levi’s daughter, unsure of her future after the death of her father and conflicted over whether to obey his dying wish; Sean Orvieto, a Jewish doctor and man of conscience, who Aldo feels drawn to; and there is the lovely Corporal Strocchi, still quite new to Florence, and still astounded at the goings on: “what was wrong with people in this city?”

The writing is atmospheric, conjuring up the chaos, stench, and darkness of Florence. The plotting is solid and engaging. There is a smattering of Italian through the text, some of which I found unnecessary and a bit coy given the subject matter: palle, cazzo, buggerone. The novel is a satisfying mystery, but also a great set-up for future Cesare Aldo adventures. One thing I am sure of now I have read City of Vengeance, is that regardless of gender, orientation, age, status, or religion, I am glad I didn’t live in Florence in 1536!