Wetherby had decided to keep his visit to Washington very low-key so, unusually, no one met him at the airport. After the usual lengthy wait, Immigration accepted him for who he said he was: Edward Albright, a London businessman in town for a couple of meetings, staying just the one night.

He’d picked a hotel in Virginia, on the airport side of the city, not far from Langley, where he was due first thing in the morning. With any luck he’d catch the early-evening flight back to London the following day.

His hotel, one of a vast American chain, was comfortable, clean and entirely soulless. He phoned home and spoke to Joanne who, five hours later, was getting ready for bed. Then he ate an early dinner in the hotel restaurant – an overcooked steak and a glass of California cabernet. Back in his room, he lay down for a while on one of his room’s two large double beds and clicked idly through what seemed to be several thousand television channels.

He thought with amusement how he could have squeezed the entire Wetherby family into this ample room. When the boys were small, they’d often stayed in more cramped quarters on their trekking holidays in Europe. They’d made walkers of the boys early on, and he remembered fondly how the then-healthy Joanne had put them all to shame when it came to stamina in the Tuscan hills or Pyrenees, where they’d go for two weeks in August. Now, he thought sadly, she ran out of puff after twenty minutes in their garden.

In the morning he made the short drive to Langley, stopped at the security sentry post, then parked his hired car where he was directed near the headquarters building. The CIA’s director of counter intelligence was Tyrus Oakes, a long-time Agency veteran, lacking any public profile but famous within the halls of Langley. He had many quirks, most notably a habit of taking voluminous notes throughout even the most pedestrian meeting, all collected on the yellow legal pads that American attorneys in pre-computer days had used to compose their briefs.

Physically, too, he was unusual – a small, slight man with a razor-edged nose and big ears that protruded from each side of his head like satellite dishes. To his friends, mainly fellow senior officers, he was known as Ty; to those who knew him only by repute, he was The Bird.

Wetherby had come to realise over the years that the different reactions he sometimes received from Oakes had nothing to do with Wetherby’s position as an intelligence officer of a foreign country, but only with the extent to which he shared Oakes’s views about the matter under discussion. This gave Wetherby slight forebodings about his forthcoming conversation, since he couldn’t believe Oakes was going to be very happy with what he had to say.

‘Charles, it’s real good to see you.’ Oakes came out from behind the desk.

‘And you, Ty.’

‘Take a seat,’ said Oakes, pointing to a chair in front of his desk, while he retreated behind it. He said, ‘This must be kind of important for you to fly over.’

‘It is. I think we may have a serious problem.’

Wetherby outlined the sequence of events as succinctly as he could. As he spoke, Oakes rapidly discarded his yellow pad, fishing out of his pocket a small spiral-bound notebook, in which he wrote quickly in tiny writing, lifting his head occasionally to look at Wetherby.

At least he’s not moved to a laptop, thought Wetherby, as he continued his account of Fane’s relayed message from Jaghir, that two rogue elements were acting against Syrian interests in London, and were threatening to sabotage the impending peace conference.

Oakes’s eyes widened at this, then widened further still when Wetherby recounted the attempt to run down one of his female officers with a car. He stopped writing momentarily, then resumed, head down, scribbling furiously, though when Wetherby explained that Jaghir had been killed the week before in Cyprus, Oakes stopped writing altogether. This time he even put his pen down.

Wetherby said, ‘Here’s where the difficulty starts. All this information about a threat was held very tightly. In MI5, fewer than half a dozen officers were indoctrinated and Geoffrey Fane has said that in his service it was strictly “need to know”. But the attack on my officer, and now the murder of Jaghir, makes it look as if there’s been a leak. The only others told were two of your officers in Grosvenor Square.’

Oakes looked up again, but didn’t speak.

‘I’m not suggesting anything. Just stating facts. And I’m sure you’ll understand that we had to look into this. After all, one of my officers was almost killed.’

Oakes nodded. Wetherby continued: ‘Fane talked with two of your officers there. Andy Bokus and Miles Brook-haven.’

‘I know them,’ said Oakes noncommittally.

‘We’ve had dealings with both of them, of course, on many things, and Brookhaven has been liaising with one of my officers on this business.’ He added flatly, ‘The same officer, in fact, who was almost killed.’

Oakes frowned, but remained silent. Wetherby went on, ‘We noted, too, that Brookhaven had recently come from Syria. A coincidence we felt compelled to pursue.’

‘So you put him under surveillance,’ said Oakes bluntly. It was not a question.

‘I’m sure you would have done the same. We get particularly concerned if people are undeclared. For example, somebody we’ve been watching recently is a man named Kollek. He’s an attach? at the Israeli Embassy, and is supposed to be a trade officer. But we’re confident he’s actually with Mossad.’

Oakes looked puzzled. ‘I don’t follow you, Charles. What has this got to do with Miles Brookhaven?’

‘Nothing whatsoever, and that’s not why I’m here. Last Thursday one of our teams followed Kollek to a cricket match in south London. Funny place for an Israeli to go, we thought. But he wasn’t there for relaxation.’ An envelope materialised in Wetherby’s hand and he handed it across the desk. ‘Have a look, if you don’t mind, Ty.’

And he watched as Oakes extracted the photographs and looked at each in turn. You had to hand it to him, thought Wetherby, Oakes made a good show of looking unperturbed. But when he put the photographs down Wetherby noticed Oakes’s right hand was tensed into a fist.

Oakes said, too casually to convince, ‘There could be a perfectly innocent explanation for this.’ He stared directly at Wetherby, but his eyes were curiously unfocused.

‘Of course there could. It’s just that in that case, we would like to know what it is.’

Oakes pursed his thin lips, then put a hand to his forehead, the first indication of the tension Wetherby knew he must be feeling. Oakes said quietly, ‘I’ve known Andy Bokus a long time.’ He sighed, as if he knew this was irrelevant. ‘I don’t know what to say, Charles. Except that these-’ and he pointed at the photographs – ‘are as much a surprise to me as they must be to you.’

They sat in silence for a long time. At last Oakes said, ‘I haven’t got an answer for you. And I’m not going to have one today – or even tomorrow. But I will have by the end of the week. Will that do?’

‘Of course.’ He rose to his feet. ‘I’ll head back to London. It goes without saying you should deal only with me on this.’

‘Understood,’ said Oakes, and Wetherby sensed that as soon as he’d left the man would spring into action.