‘No.’ Patrick almost raised his voice. ‘By which I mean that in the same way there’s no concrete evidence to link you, there’s none to link her either.’

‘She could have let someone else in,’ said Sara.

‘Yes, she could have.’ He shot her a hang-dog grin. ‘And many other things could have happened too.’ Patrick stared out again. ‘That’s the point. This is the perfect death to induce speculation. One piece of evidence, the remnants of cleanser, shows someone was with him before, during or after his death. If there was a sex act after which the cleanser was used, he may have died later, alone and innocently. So the cleanser itself does not prove a crime. Any hare can run. Russian crime syndicate, MI5 cover-up, the blackmailer he was refusing to pay. It will be unsolvable.’ He paused. ‘Let’s sit. Let’s really look at each other.’

She frowned for a second. ‘OK.’

He went back to his desk. They locked eyes. ‘It will be unsolvable,’ he repeated, ‘unless there’s something someone knows that they’re not letting on. That might begin to explain it. We don’t have that something yet. A few Muslims being taken for interrogation to a mysterious guy they only know as the Adviser or whatever doesn’t do it. A few Muslims going missing—’

‘More than a few if it’s the tip of the iceberg—’

‘Doesn’t matter how many. Not on its own. Lists of missing people in the Sayyid files, whoever they might be, don’t mean anything unless there’s a pattern. A uniting factor. Some kind of agent – individual, organisation, force, whatever – which is so significant – or has done something so out of order – that it has to remain buried for ever.’

He drew his chair even closer, the strength of his eyes and soft urgency of his voice beginning to alarm her. ‘Unless there’s something more – something that some big fish’s whole being, whatever side they’re on, depends on concealing – it stops here. Morahan’s death is just a sad accident that happened to an old man who liked the odd moment of excitement. We can’t take it any further.’

‘Yes, we could stop it here,’ she murmured.

‘Look inside yourself,’ he said. ‘Is that what you want? Be truthful.’

‘I could ask you the same question.’

‘Two days ago my answer would have been different to now.’

‘So something did change.’

‘Yes.’

‘What?’

‘It’s not relevant.’

‘I have to know.’

He cupped his face in his hands. Motionless on her seat, she waited. ‘All right. I had a visit.’

He turned away; she wondered if he was aware of his intensity. She rose and took up his former position by the window, her back to him. ‘Tell.’