The Darkest Sin by D V Bishop

If you enjoyed City of Vengeance, good news.  Cesare Aldo is back in this thrilling sequel.     Florence 1537.
 
When Cesare Aldo investigates a report of intruders at a convent in the Renaissance city's northern quarter, he enters a community divided by bitter rivalries and harbouring dark secrets. When a man's body is found deep inside the convent, stabbed more than two dozen times, the case becomes even more complicated. Unthinkable as it seems, all the evidence suggests one of the nuns must be the killer.

Meanwhile, Constable Carlo Strocchi finds human remains pulled from the River Arno that belong to an officer of the law missing since winter. The dead man had many enemies, but who would dare kill an official of the city's most feared criminal court?As Aldo and Strocchi close in on the truth, identifying the killers will prove more treacherous than either of them could ever have imagined .
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He is fast becoming a serious rival to C. J. Sansom and S.J. Parris . 

.Highly recommended' - Historical Novel Society