It was a proper shiny bolt, with a nut, and a cable coming off it to a black box with a digital display. It was the kind of nut and bolt you might see on a radiator or a bicycle wheel.

The display was giving a reading of fifty-seven.

‘Hi, Bruno,’ he said, trying to sound cheerful. ‘It’s your dad and Cleo here.’ He knelt and kissed his son’s cold, clammy cheek, stroked his forehead and then held his right hand, which was limp and tiny. ‘How are you doing, soldier?’

He studied Bruno’s face intently, but there was no flicker of reaction, his eyes firmly closed. Just a faint motion of his chest as he breathed.

Glancing around, he saw that the doctor had quietly retreated, leaving them alone.

‘Hello, darling,’ Cleo said. She kissed Bruno too, and took his other hand and held it tightly. ‘Your dad and I are here. Can you hear us?’

There was still no reaction.

They sat down in the two chairs beside the bed and talked to him for ten minutes, about school, about Humphrey, about how he was getting on with his computer games, and about the app TikTok.

After a while, the consultant returned. In a quiet voice he invited them to come out for a chat. They returned to the Relatives’ Room and sat back down.

‘This induced coma, he’s still in it?’ Grace asked.

Williams shook his head. ‘No, we ended that early last night. We’ve removed all of his sedation and drugs that would keep him asleep. This is how he is. Did you feel he responded to you at all?’

Grace looked at Cleo. She shook her head.

‘No, he didn’t give any indication,’ he said.

‘I’m afraid, honestly, you’re not going to get any reaction from him.’ Williams paused. ‘You obviously saw the intracranial bolt.’

‘It’s not a good look,’ Grace said, attempting the merest trace of humour. ‘Something out of Frankenstein.’

The consultant continued his sympathetic expression, nodding. ‘It performs an essential task of telling us the pressure inside his skull. I know it was explained to you earlier, but the higher the pressure from the swelling brain, the more it crushes the vital brainstem. In a normal, healthy brain, a reading of five to fifteen millimetres of mercury is normal. We consider badly raised pressure to be above twenty-five.’ He hesitated a moment, then said, ‘As you may have seen, Bruno’s current reading is fifty-seven, and it is rising steadily.’

Cleo was about to reply when the door opened and they were joined by two women in regular clothes. One was in her fifties with an earnest expression and reminded Roy of the actress Helena Bonham-Carter; the other, twenty years her junior, had a slim figure, a tangled frizz of bleached hair and striking features.

‘Mr and Mrs Grace,’ Williams said, a little stiffly, ‘if I could introduce Imelda Bray, our resident counsellor, and Charlotte Elizabeth, who is our transplant coordinator.’

‘Excuse me, who?’ Grace said, looking confused.