Kate finished her tea and tipped the dregs on to the gravel by her feet. ‘What really troubles me,’ she said, ‘is Sergei. These past few days, I’ve been obsessed by trying to work out who in SIS could have been aware of the true nature of my friendship with him.’

‘Why?’

‘Because the entire operation was predicated on me trusting his motives. And there is no way Igor Borodin would have gone to such lengths unless he was damned sure I’d swallow it.’

‘So it had to be someone who knew you well enough to be certain of that connection,’ Rose said.

‘I was thinking that. But then I had another idea, which was a lot more disturbing.’

‘Which was that Sergei was not an unwilling pawn of his bosses in Moscow, but the architect of the entire business?’

Kate didn’t answer, but this was precisely the fear that had consumed her on the journey back from Sir Alan’s home in Hampshire. How could she have been so naive? She had even considered the possibility that his death in that train carriage in Russia had in some way been faked. After all, had she taken the trouble to check his pulse and ascertain beyond doubt that he was indeed dead?

Rose put the top back on her Thermos and placed it in her bag. She stood. ‘I don’t have an answer to that question. And I don’t suppose you’re going to find one either, any more than, at this stage, you’re ever going to sift fact entirely from fiction in this case. The Russians are now so good at confusing the very nature of truth that I’d say you’d be better off moving on and making a success of the rest of your life.’ She offered her hand. ‘But there is a young girl half a mile away whose world you’ve totally transformed and that’s the kind of truth we all need more of.’

Kate took her aunt’s proffered hand and hauled herself wearily to her feet. They walked the half-mile to the small terraced house in silence, through the commuters hurrying home before the rain set in. Thunder rumbled in the distance.

They hesitated by the newly painted front door, their feet by a mat that proclaimed its welcome in large, untarnished black letters. Rose knocked. They heard voices inside. Rose gave Kate an uncharacteristic wink and Kate returned her smile. ‘Cheer up,’ Rose said. ‘Not everyone gets to save a soul from a life of purgatory. It might even be enough to impress St Peter, when the time comes.’

‘I’ll need something.’

‘So will I.’ Rose smiled at her again as the door was opened by a slim, neatly dressed man of indeterminate age with thick glasses and skin scarred from adolescent acne. The woman who came into view behind him wore the nervous smile of all arrivals unsure of the welcome their new home will offer.

They introduced themselves as Alexander and Zara and their servile gratitude immediately grated. What on earth, Kate thought, did any of them really have to thank her for?