I followed her. She moved with the careful deliberation of someone whose body has betrayed them. I waited until she had sunk into an armchair, and then took my place on the sofa opposite. An ancient black Labrador padded silently into the room, sniffed the hand that I offered and then ambled over to settle on its owner’s feet.

The Filipina housekeeper appeared.

‘Tea, please, Rosalita,’ said Mrs Jones. Then she looked at me with her shining eyes, bright blue behind her spectacles, intelligent eyes that were still shocked with grief. ‘I do appreciate you coming,’ she said. ‘And how are your enquiries progressing? Have you arrested anyone yet?’

‘No, ma’am,’ I said. ‘But if you could answer some questions, that would be an enormous help to our investigation.’

She nodded, her hand absent-mindedly stroking the back of the black Lab’s neck. The dog grunted with contentment.

‘Your son,’ I said, ‘Adam. It would be helpful if you could tell me about Adam.’ I hesitated. ‘He had no fixed abode at the time of his death?’

His mother smiled, remembering an earlier time.

‘He was a very gifted boy,’ she said. ‘Enormously talented. Sensitive. A wonderful musician. Wonderful!’

She looked around the room, and now I saw that it was a shrine to her dead son. On the bookshelves were trophies, prizes, and small white busts of men having bad hair days. Beethoven and the boys. Between the shelves the walls were covered with framed certificates. And massed on top of a small piano was an array of silver-framed photographs.

‘My son was at the Royal Academy of Music,’ Mrs Jones told me. ‘For one term. Before they asked him to leave.’

Rosalita brought our tea. Mrs Jones lifted a hand and the housekeeper understood that we would serve ourselves. I waited until she had left the room.

‘Why did they ask Adam to leave?’

Mrs Jones ruffled the dog between the ears, her face clenched with tension, and I saw that she was in what must have been constant pain.

‘Because,’ she said, ‘there was a darkness in him.’ She smiled with an old sadness. ‘I don’t know how else to explain it. There was a darkness in my son, and that led him to the drugs. And then the drugs took away everything.’

‘I think he was trying to stop,’ I said. ‘The autopsy showed there were no drugs in Adam’s body at the time of his death.’

‘Yes, he was trying to stop. He was trying very hard.’ She looked at me. ‘Thank you,’ she said.

I wasn’t sure what she was thanking me for, and I didn’t know how to respond.

Mrs Jones poured our tea. I looked out of the windows. The fox had gone.

‘When was the last time you saw your son?’