In the next three days the weather changed completely and they flew out of Northolt on a hazy blue spring morning, the little twin-jet Dominie rocking and humming in the new west wind. It was too early to be the real spring, but it was a hint, perhaps a promise.

Tyler spent the flight sipping RAF coffee poured from a vacuum flask and letting papers stack up in his lap. He would take one, glance at it, then his gaze would drift back to the little window and the misty patchwork of Belgium, 25, 000 feet below.

"That's where it happened," he said in his deep slow voice, "where it's always happened. The Sambre, Ramillies, Mons, Ypres, Liиge, the Ardennes… Belgium's dark and bloody ground. From Caesar to General Patton in about five minutes flying time…"

He turned and caught Maxim's eye and smiled across the narrow aisle between the fat VIP seats. He had been talking mostly to himself, but Maxim was the one who would understand.

Tyler added: "I was with Monty's TAC HQ back near St. Trond then. It was quite an interesting Christmas."

"It must have been." That was when Patton had disengaged three divisions from action – tricky enough in itself – then swung them and his whole army with its hundred thousand vehicles through ninety degrees and rammed them north across seventy-five miles of icebound roads straight into the new Battle of the Bulge. All in four short-lit December days. That was what professional soldiers remembered about Patton, not the circus trappings of the two pistols and the bragging.

The Dominie's engine note wound down and they began a gentle slide down the hill of air. Mrs West, the solid quiet-eyed secretary borrowed from Defence, handed Tyler another paper and watched impassively as he let it join the stack in his lap. He was wearing, Maxim noticed, the scarlet thread of the Lйgion d'honneur in the lapel of his usual hairy dark suit.

The RAF steward came back, stooping in the low cabin, and asked cheerfully: "Would anybody like another cup of coffee? We'll be landing in Luxembourg in approximately fifteen minutes."

They all shook their heads, No Thanks, and the man from the Foreign Office said to Maxim: "Anybody would think the Grand Duchy of Luxembourg had never heard of coffee for itself. Anyway, at four in the afternoon…"

He was about Maxim's own age, and his name was Stephen Quinton. He had a round, freshly-washed face, very fine blond hair, and was along, Maxim guessed, to see that an amateur like Tyler didn't make a fool of himself in what were indisputedly Foreign Parts, never mind any Lйgion d'honneur or nonsense like that.

"Have you ever been in Luxembourg?" Quinton asked.

"No, never."

"It's an odd place, really…"

"Does it give you vertigo?"

"No. No, I wouldn't say that;" Quinton had a permanently puzzled expression, as if he were always about to ask somebody to say that again but more slowly. "Why do you ask?"

"Just something a friend said."

"Oh. I don't think you'll find that…" He chattered on, perhaps nervously, as the Dominie slanted downwards.

The little aeroplane stopped less than halfway down the vast runway that was itself a far greater contribution to NATO than Luxembourg's 630-man army. If Der Tag ever dawned, this was one of the 'mobilisation bases', built to take the biggest American transport aircraft that would flock in with reinforcements – unless a Russian missile or air strike had got here first, of course. Meanwhile, it was the tidiest airport Maxim had ever seen: the grass was cropped to the bone and the runway edges trimmed as neatly as any royal garden.

There was a brief unceremonial ceremony behind the cargo sheds, out of sight of the main terminal, then they were hustled into two hired Mercedes and skimmed off towards the city.

Maxim shared a car with the British ambassador, Tyler and a stolid middle-aged captain with careful eyes who came from the Sыretй Publique.

"Has there been any reaction here, yet?" Maxim asked.

"There was a small demonstration outside the embassy a couple of days ago," the ambassador said. "And I believe today…" he nodded at the captain.

A shrug. "A few protestors with notices were at the main gate of the airport. Nothing of importance." Speaking English, he had a dull flat voice like a government document.

"Do they know where the talks will be?"

"They will guess. Senningen is the only place. It is not the Luxembourgeoise to worry about, it is the terrorists from the outside. We have changed the hotels, but…" Another shrug.

"Thank you," Tyler said firmly, staring at Maxim.

For real secrecy they should all have arrived in darkness, to hide the national markings on their aircraft; they should have stayed at some easily defended, unexpected, country house; they should have travelled – if at all – using all sorts of decoy cars and helicopters. But as George had said, to try and paint back on all the secrecy that had been stripped off would make the talks seem even more sinister. Whatever Moscow really felt, Washington was showing alarm and despondency. Now they could only hope for security and forget secrecy.

The hotel was elderly and comfortable without trying to be grand. But on the short ride in from the airport, Maxim had guessed that Luxembourg liked things tidy rather than magnificent.

The men shared a suite of three rooms – Mrs West was just down the corridor – a drawing-room bracketed by two bedrooms so that any visitor had to come into the drawing-room first. Tyler took one bedroom, Maxim and Quinton the other, not very enthusiastically. For the moment, the Sыretй captain kept watch.

Quinton got even less enthusiastic when Maxim took off his jacket.

"Great Heavens, man, have you been wearing that thing… I mean on the plane and with the ambassador!"

"Yes." Maxim wriggled his shoulders inside the wide straps of the shoulder holster. "And I shall be wearing it all the time I'm with Professor Tyler."

"Who told you that you could?"

"Number 10."

That was the Word of Power. "Well, I just hope you know what you're doing. I didn't know you'd got the beastly thing at all."

"You're not supposed to notice. D'you want the bathroom first?"

"No, go ahead…" Quinton sat on the edge of the bed, shaking his head in little shivery movements. And he didn't even know he'd missed Maxim shifting the gun to his raincoat pocket so that he could get off the aeroplane with a sensibly buttoned-up coat. Or changing it back in the hotel lift.

It wasn't his fault. You see what you expect to see, and ninety-nine per cent of the world doesn't expect to meet people carrying concealed weapons. The one per cent constitute the problem.

That evening there was a buffet supper, an informal first meeting of the delegations, at another hotel across in the old town, near the station.

Given time to look around, Maxim saw, as they ran out on a long bridge over one of the city's sheer-sided ravines, just what George meant about vertigo. Down there, far down, was a gentle river in formal gardens and flanked by-a sprawling village, its lights winking mistily in the blue dusk. But above, the stolid palaces and offices stared at each other across the quarter-mile canyon as if it simply wasn't there, something they would rather not see and certainly not talk about, like a nasty birthmark.

The supper was quiet, restrained. Tyler and the French delegate knew each other, but from what Maxim could hear, they stayed away from the topic of the talks. He spent most of the time talking jigsaw German and English to a Luftwaffe colonel who was dogsbodying the German main delegate. At ten o'clock, the party began to melt away.

They had come in one car – Mrs West had either not been invited or ducked out – and as they reached it, Tyler said: "You go ahead. I'm going to walk for a bit."