‘Thank God it’s you, old man,’ Williams said when he finally released Knox from his embrace but kept a tight grip on his shoulders.

Old man was a private joke between Knox and Williams, an ironic reference to the world of club room conversations and gentleman’s agreements they’d found themselves part of as young, fast-rising members of MI5. Hearing it again after so many years warmed Knox’s heart, and sliced straight through it.

‘Expecting someone else?’ Knox asked.

‘Honestly,’ Williams replied, ‘I had no idea.’

He seemed completely transformed from the fragile figure in Regent’s Park. His voice was now full of humour and energy. He let go of Knox and walked over to a low line of dusty crates.

‘I woke up about ten minutes ago. No idea how I got here. But that seems pretty par for the course at the moment.’

‘Well, I’m glad you stuck around,’ Knox said, relieved but also concerned that Williams didn’t seem to know how he’d made his way to Smithfield after jumping on the backboard of the bus on Ulster Terrace and crouching between its rear seats out of Bennett’s view.

‘I decided someone would arrive sooner or later and tell me what was going on.’ He paused for a moment, then added, ‘I’m glad it was you.’

‘Do you remember Regent’s Park?’ Knox asked.

‘Of course,’ Williams replied, an edge suddenly creeping into his voice. ‘Most of it, anyway.’

‘Who was there with us?’

‘Abey Bennett. My mind’s not a complete wreck.’

‘Sorry,’ Knox said. ‘I know this must be frustrating, but I need to ask you a few more questions.’

He joined Williams on the row of crates as the rumbling echo of a tube train hummed through the store.

‘What about before the park?’ he asked.

‘There are shards, fragments of places and people, but I don’t know when or where it all belongs.’

‘That doesn’t sound like much fun,’ Knox said.

‘It’s bloody terrifying,’ Williams replied, his voice softening again. ‘But what can I do?’

It was a sad statement, but in a strange way it reassured Knox because it was exactly what he’d expect Williams to say.

He remembered the waxed paper parcel he was holding and handed it over, watching Williams’s face twist into a grin as he unwrapped the pie and devoured one of the thick wedges it had been cut into.

Knox knew he should give Williams a chance to eat, rest, build up some strength, and hope more of his memories fell into place. However, he was too impatient to ease off for long. He wanted to know more about the attack Williams was so scared of, and where his best friend had been for the last seven years. But not in that order.

‘What’s the last thing you remember from before….’ he started, but was suddenly unable to complete the question.