Most of the early results were irrelevant, but as I scrolled down and down, I came at last to a local-interest blog, written by some sort of amateur historian.

“STRUAN—Struan House (now renamed Heatherbrae), near Carn Bridge in Scotland, is another curiosity for garden historians, being one of the few remaining poison gardens in the United Kingdom (another being the famous example at Alnwick Castle in Northumberland). Originally planted in the 1950s by the analytical chemist Kenwick Grant, it is thought to feature some of the rarest and most poisonous examples of domestic plants, with a particular focus on varieties native to Scotland. Sadly, the garden was allowed to fall into disrepair after the death of Grant’s young daughter, Elspeth, who died in 1973, age eleven, having, according to local legend, accidentally ingested one of the plants in the garden. Although in its day occasionally open to researchers and members of the public, Dr. Grant closed the garden completely after his daughter’s death, and after he himself passed away in 2009, the house was sold to a private buyer. Since the sale, Struan has been renamed Heatherbrae House, and it’s believed that it has been the subject of extensive remodeling. It is unknown what remains of the poison garden, but it is to be hoped that the current owners appreciate the historical and botanical importance of this piece of Scottish history and maintain Dr. Grant’s legacy with the respect it deserves.”

There were no photographs, but I returned to Google and typed in “Dr. Kenwick Grant.” It was an unusual name, and there were few results, but most of the pictures that came up seemed to be of the same man. The first was a black-and-white picture of a man aged perhaps forty, with a neatly clipped goatlike beard and small wire-framed spectacles, standing in front of what looked like the wrought iron gate of the walled garden where Maddie, Ellie, and I had entered the day before. He was not smiling, his face had the look of one that didn’t smile easily, with an expression naturally serious in repose, but there was a kind of pride in his stance.

The next photograph made a sad contrast. It was another black-and-white shot, recognizably the same man, but this time Dr. Grant was likely in his fifties. His expression was totally different, a distorted mask of emotion that could have been grief, or fear, or anger, or a mix of all three. He seemed to be running towards an unseen photographer, his hand outstretched, either to push the camera away or shield his own face, it was not clear which. Behind the goatlike beard his mouth was twisted into a snarling grimace that made me flinch, even through the tiny screen, and the passage of decades.

The final photograph was in color, and it was a shot that seemed to have been taken through the bars of a gate. It showed an elderly man, stooped and bent, wearing a buff overall and a wide-brimmed hat that shaded his face. He was extremely thin, to the point of emaciation, and leaning on a stick, and his glasses were thick and fogged, but he was staring fiercely at the person taking the photo, his free hand upraised in a bony fist, as though threatening the viewer. I clicked on the picture, trying to find out the context for the shot, but there was none. It was just a Pinterest page, with no information on where the picture had been found. Dr. Kenwick Grant, the caption read, 2002.

As I closed down the phone, my overwhelming emotion was a kind of desperate sadness—for Dr. Grant, for his daughter, and for this house, where it had all happened.

Unable to sit in silence with my thoughts any longer, I got up, put the baby monitor in my pocket, and, grabbing a ball of caterers’ string from the drawer by the cooker, I left the house by the utility room door, tracing the path the girls had shown me the day before.

* * *

The sun of the morning had gone in, and I was cold by the time I reached the cobbled path that led to the poison garden. It was strange to think it was June—down in London I would have been sweating in short skirts and sleeveless tops, and cursing the shitty air-con at Little Nippers. Up here, almost halfway to the arctic circle, I was beginning to regret not taking my coat. The baby monitor was silent in my pocket as I reached the gate and slipped my hand through the metalwork to try to trip the catch, as Ellie had done.

It was more difficult than she had made it look. It was not just the fact that the hole in the wrought iron was too narrow for my hand to fit comfortably, it was also the angle. Even after I had forced my hand through, swearing as the rust ripped skin off my knuckles, I could not get my fingers to the catch.

I changed position, kneeling on the damp cobbles, feeling the chill strike up through the thin material of my sheer tights, and at last managed to get a fingertip to the tongue of the latch. I pressed, pressed harder . . . and then the gate opened with a clang and I almost fell forward onto the worn bricks.

It was hard to believe that I had ever mistaken it for a regular garden. Now that I knew its history, the warning signs were everywhere. Fat, black laurel berries, the thin needles of yew, straggling patches of self-seeded foxglove, clumps of nettles, which I had taken to be weeds when I first entered the garden but which I now saw bore a rusted metal tag dug deep into the earth labeled Urtica dioica. And others too that I did not recognize—a plant with flamboyant mauve flowers, another that brushed my leg with a sensation like tiny needles. A patch of something that looked like sage but must have been something very different. And, as I pushed open the door of a tumbledown shed, a profusion of mushrooms and toadstools, still sprouting gamely in the dark.

I could not suppress a shudder as I drew the door quietly shut, feeling the damp wood grate on the flags. So many poisons—some tempting, some decidedly not. Some familiar, and some I was certain I had never seen before. Some so beautiful I wanted to break off a branch and stick it in a jug in the kitchen—except that I did not dare. Even the familiar plants in these surroundings looked strange and ominous—no longer grown for their lovely flowers and colors, but for their deadliness.

I hugged my arms around my body as I walked, partly to protect myself, but the garden was so overgrown that it was impossible to avoid brushing up against the plants completely. The touch of the leaves felt like prickles on my skin, and I was unable to tell anymore which plants were toxic to touch, or whether it was pure paranoia on my part that sent my skin itching and tingling when I brushed past.

It was only when I turned to leave that I noticed something else—a set of pruning shears, sitting on the low brick wall holding back one of the beds. They were new and bright, not in the least rusted, and looking up, I saw that the bush above my head had been pruned—not much, but enough to clear the path. And further up, I saw that a piece of garden twine had been used to hold back a swag of creeper.

In fact, the more I looked, the more I was sure—this garden was not as neglected as it appeared. Someone had been tending to it—and not Maddie or Ellie. No child would have thought of neatly cutting back that hanging branch—they would have snapped it off, or just ducked under it, if they were even tall enough to notice.

So who then? Not Sandra. I was sure of that. Jean McKenzie? Jack Grant?

The name sounded in my head with a curious chime. Jack . . . Grant.

It wasn’t an uncommon surname, particularly around here, but . . . still. Dr. Kenwick Grant. Could it really be coincidence?

As I stood, wondering, the baby monitor in my pocket gave a little grumbling squawk, recalling me to reality, and I remembered what I had come here to do.

Picking up the shears, I hurried back to the gate, and pulled it firmly shut behind myself. The clang as it closed set a flock of birds rising into the sky from pine trees up the slope, and seemed to echo back at me from the hills opposite, but I was in too much of a hurry now to care.