Father allows himself a wry smile. “Some consider him to be the greatest botanist of the century. I find his work useful, though no doubt future generations will call it primitive. I can instruct you in it if you like.” He sweeps his hand around. “Bear in mind that what I have done here is, at best, an approximation of a true botanical garden, but that is because of the unusual nature of my collection. There are many plants here that have been collected from the farthest parts of the globe. Despite all my research, my knowledge of the relationships between them is scanty. Perhaps you will be able to enlighten me on that account, Weed.”

Father does not wait for an answer. “Let us start our walk here, along the east wall. These are plants you may be familiar with. Some are native to England, and some were brought over from the American colonies a century ago—the United States of America, I suppose I ought to call it now. This plant, for example. Do you recognize it?”

“Angel’s trumpet,” Weed breathes. “A plant of many dreams.”

Father looks at him sharply. “Dreams, yes—some might say hallucinations. Angel’s trumpet, also known as datura. They say the name ‘datura’ comes from a Hindu word meaning ‘thorn apple’—but perhaps you already knew that.”

Weed presses his forehead with both palms and squeezes his eyes shut. Does he not know, or is he trying to rid himself of what knowledge he has?

“A craggy old fellow I met at the St. James fair told me that tidbit of lore,” Father continues. “He specialized in plants of the Orient, and claimed to be a survivor of one of Captain Cook’s expeditions. I suspect he was lying about that, but the specimens he offered were quite rare. And the prices he charged were exorbitant, I must say.”

Father continues to stroll as he talks. He seems fully at ease here inside his locked garden—more at ease than I have ever seen him, in fact. “This is henbane. And this is poison hemlock. A painless death, but a particularly cruel one, don’t you think?”

“From the feet it begins,” Weed intones.

Father nods. “Death starts from the feet and travels upward, until it reaches the heart and finally kills you, and the whole time you are fully aware of what is happening. They say it took poor Socrates twelve hours to die. Ah, here is a favorite of mine: wormwood, the ingredient that gives absinthe its peculiarly intoxicating properties.” Father waves me closer. “Take a good look at the white bryony, Jessamine. It is all too easy to mistake its roots for parsnip. That would be the last bowl of soup any of us would ever enjoy.”

We follow Father from plant to plant. “Bittersweet,”he points out, “and adder’s root, and mandrake. And this potent specimen is called oleander—”