“Sounds complicated,” I said.

“Not really,” Luca replied. “They exist all over the place. Those alarm things in shops that go off if you try and take things out without paying, they use RFIDs. They simply have the tags on the items, and the scanners are the vertical things by the doors you have to walk between. Also, the tube and buses in London use them in the Oyster cards. You put the card on the scanner, and it reads the information to make sure you have enough credit to travel. They’re very clever.”

“So I see,” I said.

“Not everyone is keen on them, though,” he went on. “Some call them ‘spychips’ because they allow people to be tracked without their knowledge. But I think they’ll soon be on everything. You know, instead of bar codes. The supermarkets are already experimenting with them for checkout. You only have to walk past the scanner and everything is automatically checked out without you even having to take it out of the cart. One day, your credit card will be scanned in the same way, and the total deducted from your bank account without you having to do anything except push the whole lot out to your car, load up and drive away.”

“Amazing,” I said.

“Yeah. But the trouble is that, theoretically, the same RFIDs could also be used to tell the cops if you broke the speed limit on the way home from the store.”

“Surely not,” I said.

“Oh yes they could,” he said. “They already use RFIDs in cars to pay road and bridge tolls in lots of places-E-ZPass in New York, for one. It’s not much more of a step for them to calculate your average speed between two points and issue a ticket if you were going too fast. Big Brother is definitely watching you, and, even if he isn’t now, he will be soon.”

“How do you know so much about these RFID things?” I asked.

“Studied them at college, and I also read electronics magazines,” he said. “But I’ve never seen one this small before.” He held up one of the tiny glass grains.

So why, I thought, had my father had ten of them in his luggage? Perhaps they were something to do with the photocopied horse passports.

“Is the black remote thing a scanner?” I asked.

Luca pointed it at the chip and pushed the ENTER button. The red light came on briefly and then went off again, just as before.

“It doesn’t have any sort of readout, so I doubt it,” said Luca. “I’ll ask at my electronics club, if you like.”

“Electronics club?” I said.

“Yeah. Mostly teenagers,” he said. “Making robots or radio-controlled cars and such. Every Friday night in the local youth center in Wycombe. I help them out most weeks.”

I thought about whether I should give the device to him, or to the police, along with the money.

“OK,” I said. “Ask at your club if anyone knows what it’s for. Take the glass grains as well, in case they’re somehow connected.”

“Right,” he replied, smiling. “We love a challenge. Can we take it apart?”

“I suppose so,” I said. “But make sure it goes back together again.”

“Right,” he said again. “I’ll take it with me tonight. I’ll let you know in the morning if we get anywhere.”

I dropped Luca and Betsy in High Wycombe, and then I went to see my grandmother.

Her room at the nursing home in Warwick was a microcosm of my childhood memories. On the wall over her bed was a nineteenth-century original watercolor of a child feeding chickens that had once hung over the mantelpiece in the family sitting room. Photographs in silver frames stood alongside little porcelain pots and other knickknacks on her antique chest of drawers as they had always done in my grandparents’ bedroom. A framed tapestry of the Queen in her coronation coach shared wall space with a hand-painted plate that I had given them in celebration of their ruby wedding anniversary.

Each item was so familiar to me. It was only my grandmother herself who was unfamiliar. As unfamiliar to me as I sometimes was to her.

“Hello, Nanna,” I said to her, leaning down and kissing her on the forehead.

She briefly looked up at me with confused recognition and said nothing. The nurses told me that she could still chat away quite well on some days but not at all on others, and I personally hadn’t heard her speak now for quite a few weeks.

“How are you feeling?” I asked her. “Have you been watching the racing on the television? And the Queen?”

There was no reply, not a flicker of apparent understanding. Today was clearly not one of her good days.

The decision to place her in a nursing home had been both a difficult and an easy one. I had realized for some time that she had been losing her memory but had simply put it down to old age. Only when I was contacted by the police, who had found her wandering the streets in her pink nightie and slippers, had I taken her to the doctor’s. There had been a period of testing and several visits to neurologists before a diagnosis of Alzheimer’s had been confirmed. Sophie had abdicated all responsibility in the caring department, which was fair enough as she had her own problems to worry about, so I arranged for a live-in nurse to look after my grandmother in her own house. I was determined that she shouldn’t have to live in a care home full of old people who sat in a circle all day staring at the floor.

Then one day, when I went to spend an evening with her, she became very agitated and confused. She didn’t seem to know who I was and continually accused me of stealing her wedding ring. It was more distressing for me than it was for her, but it was her live-in nurse who was the most upset.

The poor girl was totally exhausted from the ever-increasing workload and was at the end of her tether. Between bouts of tears, she had told me what life for my grandmother was really like. Above all, she was lonely. Keeping her in her own home had been no real kindness to anyone, and certainly not to her. So the following day I had made arrangements for my grandmother to go into permanent residential care and had promptly sold her house to pay for it.

That had been two and a half years ago, and the money was starting to run out. I hated to think what would happen if she lived much longer.

As usual in the evenings, she was sitting in her room with all the lights full on. She didn’t like the dark and insisted that the lights be left on both day and night. As it was, on this midsummer day, the sun was still shining brightly through her west-facing window, but that made no difference to her need for maximum electric light as well.

I sat down on a chair facing her and took her hand in mine. She looked at my face with hollow, staring eyes. I stroked her hand and smiled at her. I was beginning to think this had been a waste of my time.

“Nanna,” I said to her slowly, “I’ve come to ask you about Peter. Do you remember your son, Peter?”

She went on looking at me without giving any sign that she had heard.

“Your son Peter,” I repeated. “He got married to a girl called Tricia. Do you remember? They had a little boy called Ned. Do you remember Ned? You looked after him.”

I thought she hadn’t registered anything, but then she smiled and spoke, softly but clearly. “Ned,” she said. “My little Ned.”

Her voice was unchanged, and I felt myself welling up with emotion.

“Yes,” I said. “Your little Ned. Nanna, I’m right here.”

Her eyes focused on my face.

“Ned,” she repeated. I wasn’t sure if she was remembering the past or whether she was able to recognize me.

“Nanna,” I said, “do you remember Peter? Your son Peter?”

“Dead,” she said.

“Do you remember his wife, Tricia?” I asked her gently.

“Dead,” she repeated.

“Yes,” I said. “But do you know how she died?”

My grandmother just looked at me with a quizzical expression on her face.

Finally she said, “Secret,” and put one of her long, thin fingers to her lips.