In City of Masks (Pegasus Crime, July), Sykes transports her 14th-century sleuth, Oswald de Lacy, to Venice.

Why choose the 1350s as the setting for your series?

Moments in history don’t come much more vivid and powerful than the time of the Black Death. I was inspired by a graph (I don’t imagine that many writers can make such a claim!) showing population growth in England in the 14th century; in 1348, the population had grown to around five million people, but then in two years, half of the population had died of the plague. My books are set in the aftermath of this plague: a time of sadness and devastation, but also a time of opportunity and change.

What were some of those changes?

There was a shortage of people to work in the fields and on the farms, so the poor could demand higher wages. Women were temporarily able to step into the shoes of their dead fathers, husbands, and sons—running their farms and taking over their trades. And there were unexpected opportunities for those younger sons who had previously been excluded from having any real power and authority in their families. Oswald was destined to become a monk, but on the death of his older brothers, he is pulled out of the monastery where he has spent most of his life and given the powers and responsibilities of a lord.

Why did you send Oswald to Venice?

At the time, Venice was considered a modern industrial power. She controlled much of the trade from East to West, and was also central to the business of pilgrimages. Oswald’s pilgrimage allowed me to take him away from his usual surroundings and test his character in new ways, and also gave me the opportunity to explore this unique and mysterious city at the very height of her powers.

How did you avoid anachronistic detection methods?

I needed Oswald in a position of authority so that he could put a stop to any attempts at mob rule. He needed to have a better-than-average understanding of the human body, and particularly the progress of decomposition once a person is dead—which is often such an important clue in a murder mystery, particularly in the age before any type of forensics. Oswald was educated in a monastery, and worked under an infirmarer (the monk in charge of the sick of the community), specifically dressing the dead for burial—thus giving him the opportunity to study the physical effects of death in the hours and days after a fatality. This knowledge and his attendant lack of squeamishness are vital to his skills as an investigator.