We did spend quite a lot of time going through the library looking for references to vagina dentata, which led me to Wolfe’s Exotica. What Polidori was to macabre death, Samuel Erasmus Wolfe was to weird fauna and what Dr. Walid calls “legitimate cryptozoology.” He was a contemporary of Huxley and Wilberforce and bang up to date with the then-latest theories of evolution. In his introduction to The Role of Magic in Inducing Pseudo Lamarckian Inheritance he argues that exposure to magic could induce changes in an organism, which could then be inherited by its offspring. Among modern biologists this sort of thing is known as soft inheritance and, if espoused, causes them to point and laugh. It sounded plausible, but unfortunately before he could complete the part of his book where he proved his theory, Wolfe was killed by a shark while taking the waters off Sidmouth.

I thought that, as a theory, it could explain the “evolution” of many of the creatures detailed in the Exotica. Wolfe had avoided mention in his theory of the genii locorum, the local gods, who most definitely existed. But I could see that if a person were to come under the influence of the vast and subtle magic that seemed to permeate certain localities, then perhaps they could be physically shaped by that magic. For example, Father Thames, Mama Thames, and even Beverley Brook, whom I’d kissed at Seven Dials.

Inherited by the offspring, I thought. Perhaps it was a good thing that Beverley Brook was safely out of temptation’s reach.

“Assuming the forensic dentistry confirms that it’s the same ‘creature,’ ” I said, “can we assume that she’s not natural? I mean, she’s got to be magical in some way—right? Which means she must be leaving a trail of vestigium wherever she goes?”

Nightingale poured more tea. “You haven’t picked up anything so far.”

“True,” I said. “But if she’s got a gaff, a nest where she spends most of her time, then the vestigia will have had a chance to build up. That should make it easier to spot, and since both attacks were in Soho, the chances are that’s where her lair is.”

“That’s a bit of a stretch,” he said.

“It’s a start,” I said and flicked a sausage at Toby, who executed a neat standing jump to catch it. “What we need is something that has a proven track record of hunting supernatural things.”

We both looked at Toby, who swallowed his sausage in a single gulp.

“Not Toby,” I said. “Someone who owes me a favor.”