"I have a feeling that it was you who somehow discovered this… happening, Major. Can you tell me…?"

Carefully and slowly, ready to be interrupted, Maxim said: "Bob Etheridge wrote a letter when he realised he was dying, that was in Canada, two years or more ago. He got the letter sent to Gerald Jackaman…"

"So Bob's dead? What happened to the letter?" Maxim speeded up. "We don't know. Etheridge died under a new name, but when we found out who he was, I went to see Colonel de Carette."

Tyler stopped dead. "You saw Henri? You can't tell me that Henri told you anything."

"He tried not to. But he didn't know I'd been in the desert as well. He's dying, by the way. Lung cancer."

Tyler gazed down the ravine. A diesel freight clanked and hooted mournfully across the railway arches, black against the stars a quarter of a mile down stream.

"I must go and see him. Major… would you say one other name, just for my peace of mind?"

"Soldat de la premiиre classe Gaston Lecat"

"Thank you, Major." Maxim might have been telling him the time. They began walking again.

After a time, Tyler said: "I made a balls of that patrol. But I still can't see what else… It went wrong step by step, you never knew where… What would you have done, Major?"

"Relied on my seventeen years of soldiering instead of your – what was it? – three, by then?" Tyler chuckled. "Yes. What else can you say?"

"I might have left Lecat at the village, to be captured."

"Yes, that of course. But I was afraid Henri might walk out on me. I don't now think he would have, but at the time I'd only known him for about a week. And perhaps I just wanted the poor boy along as evidence that we'd actually contacted the French. To salvage something… But when we were there in the sand – then what would you have done, Major?"

"I don't know. I'd have stayed out of the sand."

"I suppose so. Shall we try and get a taxi?"

As they climbed in, Maxim thought he saw a figure separate from the darkness of the bridge and move back towards a slow-moving car.

They got out across the square from the hotel, with a wide space of cafй chairs and tables and a concrete bandstand in between. A few spiky leafless trees stuck up into the cold lamplight. Tyler hesitated, restless and unassuaged, and sat down abruptly on one of the cafй chairs. His long legs sprawled spiderlike from his short thick coat.

"I suppose I ought to thank you for saving me from that… woman tonight. She wasn't really Cleopatra, was she? But Major – how are you going to save me tomorrow? Really the situation hasn't changed. Number 10 isn't going to broadcast my wartime past, no matter what I do." He began to laugh quietly.

"Don't you want these talks to go well?" Maxim hadn't sat down.

"I do, yes, But-"

Maxim swung around, placed his hands on the table, and very nearly lost his temper. "Then stop worrying about Number 10 and start worrying about me, because I know you killed Mrs Jackaman and they don't. Not yet."

"I… now really, Major, I'd like to see you prove I was in Ireland when-" He stopped suddenly.

Maxim straightened up. "It's all right, that doesn't give you away, her death was in the papers. But you pretended you didn't know about Bob Etheridge dying, and his letter. She'd been trying to sell it to you, she told me that. And I saw her car blow: it wasn't explosive, just petrol. In a funny way, de Carette told me how you did it: the way you booby-trapped the Volkswagen before the village, with the spark-plug in a petrol tin."

Suddenly tired, he sat down across the little table from Tyler, just two men in the whole empty square, where in daytime, in better weather, perhaps men argued about the fate of nations, about life and death.

"You were the only person with a motive for killing her," he said wearily. "Moscow had no reason, whether or not they'd got the letter. They probably think it was me, and I'm not sure George doesn't, either, since I burnt down her houseboat afterwards. Yes, that was me. But she told me she'd turned you down; probably she just wanted you to suffer for her husband's death. So you killed her. "

"I would have had to be in Ireland."

"I was in Ireland, the KGB was in Ireland, you can walk in and out of Ireland as free as the wind. The Army wishes you couldn't, but you can. And she'd been in touch with you, so she'd most likely managed to give away where she lived. She was just clever enough to be really stupid. The whole idea of playing footsie with the KGB was stupid."

At the corner of the square a car crept in and stopped, without lights. It was a long way off, too far for a revolver with a five-inch sight radius. Maxim felt awkwardly exposed; the entire situation was one of those dreams of being on the street in your pyjamas.

"I was trying to get you an early night," he said abruptly. "Let's do that."

"She was blackmailing me, Harry," Tyler said softly. So now he was 'Harry' again. "She was blackmailing the whole country. She was going to give that letter to Moscow-"

"Or maybe not. I almost talked her out of it. At least she was coming away with me."

"I couldn't know that."

"You didn't try to know. You could have come to us and said you were being blackmailed, that you were vulnerable. You were risking the country's position. Back walking into the sand again and hoping for the best and somebody else got killed just to keep your reputation sweet! Now get to bed!"

Quietly, Tyler stood up, turned, walked towards the hotel.

"What are you going to do?"

"I understand you're the best weapon we've got, Professor. It's my job to protect you. That's all I'm doing."

"When we first met, you said I – my book – was one of the reasons you joined the Army."

"I don't regret joining the Army."

The Chвteau de Senningen lay just past the airport, down a steep lane off the main road and discreetly tucked away in a park of evergreen trees. Less discreetly, it was now surrounded by a mesh fence on concrete posts, with a barbed-wire topping, but the guard-house was still just a cottage with neat shutters beside the windows and potted geraniums behind them.

Two soldiers with sub-machine guns waved them on through.

"A remarkably consistent country," Quinton said. "Where else would you find a guard-house like that – or a supposedly secret conference centre like this?"

At the end of the drive, this was a modestly large but thin country house, two storeys high plus little dormer windows with tiled witches' caps poking out from the steep roof. The windows were tall, with white shutters against the pinky-grey pebbledash walls, and the front door was just a set of french windows, held open by another soldier and a uniformed flunkey.

They drank coffee in a reception room just off the hallway. Most of the people there had been at last night's buffet, but Maxim couldn't remember many names. He stayed on the fringe of the gently swirling crowd, watching.

Quinton appeared beside him. "The old man's acting rather subdued this morning. Did he say anything last night?"

Maxim gave a slight shrug. "We talked about the war, about soldiering…"

"He's probably just tired. I wish you'd managed to get him into bed earlier, I must say."

"We had this conversation last night." They had, too; Quinton's reaction then had been as if Maxim had borrowed his fifteen-year-old daughter for a tour of down-town Hamburg.

"Well, it really is too bad."

"I expect he'll get an early night tonight," Maxim said soothingly, or as soothingly as he felt like being with Quinton.

At a signal Maxim didn't see, the delegates handed their cups to their juniors and began drifting back to the hallway and the stairs to the first floor, being elaborately polite about letting each other go first.