In The Poisoned Island, Lloyd Shepherd’s follow-up to The English Monster, the return to England of a botanical expedition in 1812 is the catalyst for a series of murders.

What inspired your second historical featuring Charles Horton of the Thames River Police?

In my first book, I took the real-life story of some vicious killings in the East End of London and set them against the background of England’s past as a slave-trading nation. I wanted to dramatize the staining of a nation’s soul, and a crime thriller with supernatural overtones seemed a good vehicle for that. My research led me to the door of Sir Joseph Banks—adventurer, natural philosopher, womanizer, drinker, explorer—and I realized that his fingerprints were all over English history from about 1770 to the early 19th century. His particular obsession was the economic and political utility of plants—how they could drive a nation’s wealth and a nation’s power. He was involved in developing tea production in China, in building up London’s Kew Gardens, and in the discovery and exploitation of the island paradise of Tahiti.

How did you come up with the macabre detail of the victims dying with smiles on their faces?

I wanted to visualize the pain in the pleasure and the pleasure in the pain: how the thing we desire most may be the thing that destroys us. Also, there’s more than a little nod to the Joker, of Batman fame!

Do your two novels share themes?

I think they share a single theme, actually: exploitation and its spiritual effect on the English soul. In the first, it’s the exploitation of peoples; in the second, the exploitation of places and natural resources.

What do you consider to be England’s approach to historical memory?

I’ve quoted George Orwell’s famous observation that England is like a Victorian family indulging in a ‘deep conspiracy of silence about the source of the family income.’ I love that. What I didn’t love was the outbreak of self-congratulation here in London that accompanied the 200th anniversary of the abolition of the slave trade in 1807. I asked myself why everyone wanted to feel good about having ended the trade, but no one wanted to talk about the trade itself. Pitt the Younger told the House of Commons in 1792 that ‘no nation in Europe has plunged so deeply into the guilt as Great Britain.’ He was right. Likewise, when people stroll around Kew Gardens, I’d like them to give some thought, if only in passing, to the terrible toll on other nations that some of those collections represent.