“And Peter,” I said. “Where did Peter go?”

“Dead,” she repeated.

“No,” I said. “Peter wasn’t dead. Tricia was dead. Where is Peter?”

She didn’t say anything, and her eyes had returned to their distant stare.

“Secret,” she had said. So she must have known.

I pulled the photocopy of my father’s photograph from my pocket and put it on her lap. She looked down at it. I placed the tiny photo of my mother and father at Blackpool there too.

She looked down for some time, and I thought at one point that she had drifted off to sleep, so I took the pictures and put them back in my pocket.

I stood up to leave, but, as I leaned forward to kiss her on her head, she sat up straight.

“Murderer,” she said quietly but quite distinctly.

“Who was a murderer?” I asked, kneeling down so that my face was close to hers.

“Murderer,” she repeated.

“Yes,” I said. “But who was a murderer?”

“Murderer,” she said once more.

“Who was murdered?” I asked, changing tack. I already knew the answer.

“He murdered Tricia,” she said. She began to cry, and I gave her a tissue from the box beside her bed. She wiped her nose, and then she turned and looked at me, her eyes momentarily full of recognition and understanding.

“And he murdered her baby.”

It emits a radio signal,” said Luca in the car on the way to Ascot on Saturday morning. He was holding the black remote-type thing with the buttons. “You were bloody lucky this wasn’t stolen,” he added.

“Why would it be stolen?” I asked him.

“Because the teenagers at the electronics club are a bunch of hooligans,” he said.“Most of them are only there because the courts make them go. To keep them off the streets on Friday nights. Supposed to be part of their rehabilitation. I ask you… Most of them wouldn’t be rehabilitated by a stretch in the army.”

“But what about this?” I said, pointing at the device.

“One of the little horrors had it in his bag,” he said. “God knows what he thought he would do with it. Just liked the look of it so he lifted it. They are like bloody magpies. If it shines, they’ll steal it.”

“You said it emits a radio signal,” I said. “What sort of signal?”

“Fairly low frequency,” he said. “But quite powerful. One of the staff at the club was able to set up an oscilloscope to see it.”

“What’s an oscilloscope?” I asked.

“Like one of those things in a hospital that shows the heart rate of patients,” he said. “It displays a trace on a screen.”

“But what’s the thing for?” I asked.

“I’m not sure, but I think it might be for writing information onto the RFIDs.”

“The glass grains?” I asked.

“Yes,” he said. “The end slides off.” He showed me. “And you can fit one of the grains into this hollow.” He pointed at it as I drove. “When you push the ENTER button, it sends out a signal. I think that must program the RFID with the numbers you punch into it before pushing the ENTER button.”

“Is that really possible?” I said. “There aren’t any connectors.”

“It’s easy,” he said. “Writing to RFIDs occurs all the time. When someone puts their Oyster card near one of those round yellow pads on the tube gates, the card is first scanned to determine the available credit, then the system automatically deducts the fare and rewrites the card with a new balance. Same thing on all the buses. It’s done by radio waves. It doesn’t need connectors.”

I was slightly disappointed. I had somehow hoped that the device was going to be more exciting than something that was fitted to every bus in London. But why, then, I wondered, did my father think it was necessary to hide it in his rucksack?

I yawned. Sleep had not come easily to me after my visit to my grandmother. I had lain awake for hours thinking about what she had said to me, and also how that secret must have burned ferociously in her for so long. What did you do when you found out that your son was a murderer? More to the point for me, what did you do when you found out that your father was one?

I thought back to when I had sat by my father’s body in the hospital after he had died. Was it really just four days previously? It felt like half a lifetime.

I had mourned for what might have been, for the lost years of opportunity. Somehow, even in spite of the knowledge I had gained since, I felt some form of affinity with the man who now lay silently in some mortuary’s cold storage. But what had he done? Had he really deprived me not only of himself but also of my mother, and a brother or sister as well?

I had tried to telephone Detective Sergeant Murray at Windsor Police Station, but I was told he was either elsewhere or off duty. I had left a message for him to call me, but, so far, there had been nothing.

“It’s the Wokingham today,” said Luca, rubbing his hands and bringing me back from my daydreaming.

“Sure is,” I said.

The Wokingham Stakes was the fourth race of the day on Royal Ascot Saturday, and it was one of the most lucrative races of the whole meeting for us bookmakers. It was also a popular race with the trainers, with the number of runners limited only by how many starting stalls could be accommodated across the width of the racetrack.

But it was not only a cash cow for the bookies, it was fun as well. While it was true that most bets tended to be smaller than for some of the group races, there were plenty of them, and it seemed like a happy race, with no one placing white-knuckle wagers that they couldn’t afford to lose.

Betsy went to sleep in the back and Luca looked through the Racing Post as I drove.

“Thirty runners again today,” he said. “They reckon here that Burton Bank will start favorite at about six- or seven-to-one.”

“Who trains him?” I asked.

“George Wiley,” Luca replied.

“Wiley trains in Cumbria, doesn’t he?” I said. “That’s quite a way to come. He must think he’s a good prospect. How about the others?”

Luca studied the paper. “About ten with a realistic chance, I’d say, but the Wokingham is always a bit of a lottery.” He smiled.

“How about the Golden Jubilee?” I asked. The Golden Jubilee Stakes was the big race of the day. Like the Wokingham, it was also run over a straight six furlongs and was for three-year-olds and upwards.

“Eighteen runners this year,” he said. “Pulpit Reader will probably be favorite, but, again, it’s anyone’s race. Always the same in the sprints.”

We discussed the afternoon’s races and runners for a while longer. I thought we would need the unpredictability of the Wokingham and the Golden Jubilee Stakes after the first two races of the day. The Chesham Stakes and the Hardwicke Stakes were both renowned for producing short-priced winners favoring the punter.

The previous day’s rain had swept away eastwards into the North Sea and the sun had returned, bringing out the Saturday crowd, which was streaming into the racetrack by the time we had negotiated the traffic jams and parked the car. It looked like being another busy day at the office.

Detective Chief Inspector Llewellyn and Detective Sergeant Murray were waiting for me in the betting ring.

“That was quick,” I said to the sergeant before either of them could say a word.

“What was quick?” he asked.

“Didn’t you get my message?” I asked him.

“No,” he replied blankly.

“Oh,” I said. “I left one for you this morning at Windsor Police Station.”

“What did it say?” he asked.

“Just to call me,” I said.

“And what exactly did you want to speak to my sergeant about?” the chief inspector asked in his accusing tone.

“Nothing much,” I said. “Forget it.”

I had wanted to ask Sergeant Murray for more details about my mother’s demise, but I wasn’t going to ask his boss. I didn’t want to give the chief inspector the pleasure of refusing to answer, as I was certain he would.