Willis Farjeon said, 'Bloody Yanks, Captain? Over here stealing our women and now our calculating machines. What can you do, eh, sir?'

'All right, Farjeon.'

Mary spotted some other men in more unfamiliar uniforms, with cogwheels and spanners on their shoulder boards. They stood apart from the rest. 'And those?'

'Ah. Red Army technical experts.' Mackie smiled ruefully. 'All a bit delicate, isn't it? Can't shut Uncle Joe out of what we're offering to share with the Americans. Anyway let them have the Colossus and so forth; that doesn't really matter. In fact our pals here believe this is all part of a Nazi chemical weapons research programme. Sarin and Tabun. The verzweiflungswaffen.'

'The weapons of despair,' Ernst Trojan murmured.

'A lot more plausible, don't you think? Now, look, we don't have to wait until the tower falls. What we plan to do is take this group in ahead of the main party and break into the Loom bunker itself. We've always had pretty good intelligence about this place, and we're confident that right now in the bunker there's only Standartenfuhrer Trojan and Unterscharfuhrer Fiveash. They've always kept the Loom technology to themselves – waiting to pass it on as a gift to Himmler.' He glanced at Gary and Willis. 'Two Nazis, that's all, one of them a British woman. Think we can deal with them, boys?'

Willis grinned in that disturbing way of his, face blacked. 'Show us the way in, sir.'

Gary checked his weapons, but he was more circumspect. 'I think it would be a mistake to underestimate those two. Julia Fiveash in particular.'

'I agree,' Mary said warmly. 'But I'd like to get this over before I lose my nerve altogether.'

Gary said, 'I'll keep you safe, Mom.'

'I'll stay out of the line of fire, don't worry.'

Tom Mackie said, 'Right, let's get on with it. We can reach the bunker entrance by following this trench, and then hopping over that bit of wire over there. Corporal Wooler, if you bring up the prisoner – Farjeon, you lead the way, if you would.'

Willis grinned again. 'Aye aye, Captain.' He turned and scurried down the trench.

The rest followed, splashing through mud that stained their boots with blood and oil.

The door blew in. In his chair, handcuffed, George cowered.

'Drop your weapons! Hands up, hande hoch! Drop your weapons!'

Running figures, silhouetted by daylight, came through the smoke and dust, fanning out quickly, rifles raised to shoulder height, shouting. Their faces were blackened. They were soldiers with guns, soldiers in British battledress, six, seven, eight of them, and other figures behind. Josef Trojan backed up to the Colossus machine uncertainly, his Luger in his hand.

Julia ran to George. She grabbed him under one armpit and hauled him to his feet, with a strength like a rugby player's. She pressed the barrel of her silver pistol to his temple.

And with her free hand she turned a switch on the glass tank. Ben had been struggling to stay awake; he had been fighting his restraints, if feebly. Now he was sinking into a deeper sleep. George had seen this done before, the medication automatically fed to the boy. It would take him some minutes to succumb.

One of the soldiers, blond hair under his helmet, peered into the glass tank. 'That's him, Gary, that's Ben Kamen! My God, he must be the unluckiest man alive.' He actually laughed at Ben's plight.

The other called, 'Ben, I told you I'd come back for you.' His accent was American. George recognised the voice; he couldn't believe his ears. Gary?

'Dunno if he can hear you,' the blond one said. He came closer to the tank, rifle raised.

Julia snapped, 'Another step and I'll kill the policeman and the Jew. Is that clear?'

George, dizzy from lack of food and water and sleep, crusty in a uniform he hadn't changed for two days, tried not to laugh. 'So we're reduced to this, Julia? What on earth did I ever see in you?'

His reward was an elbow in the kidney.

Another of the intruders stepped forward. He wore a peaked Navy officer's cap. 'All right, lads. Lower your weapons. Let's get this mess sorted out without anybody else dying. I said, lower your weapons.'

The others looked at him uncertainly before they complied. Julia, though, kept the pistol muzzle at George's temple.

The captain was distracted by the calculating machine. 'Look at that bloody thing. Puts my bloody bits of Meccano in the shade, Mary!'

Mary?

George called to the American soldier, 'Gary Wooler? It is you, isn't it?'

The American grinned at George, his teeth white in the black on his face. 'Should have known you'd be up to your neck in it, George.'

'I haven't heard from you since you got out of the stalag.'

'Sorry about that. Blame the Reich post. Hey, Mom. Guess who's here?'

And George was stunned when Mary Wooler stepped forward. She was wearing a blue coverall, the kind the WVS girls wore, and she had a pack on her back. Her greying hair was tied back, and her face was blacked.

'Mary? My God!'

'I suppose I should have expected you, George. You're still in thrall to Miss Fiveash here, are you?'

'Unterscharfuhrer to you,' Julia snapped.

Seeing Mary and Gary together brought memories flooding back to George, memories of Hilda he thought he had buried for good. 'I've been lost, Mary,' he said, hearing the gruffness in his own voice. 'I guess a lot of us have, this side of the Winston Line.'

'You always did your job, Sergeant,' murmured the Navy man. 'So our intelligence informs us. I'm Mackie, by the way. Captain, RN. Mary, I suggest we get on with what we came here for. We may not have time to interrogate these two. But the documentation here – look, there are heaps of it – that may be enough to tell us how far they've got.'

Mary walked to a set of shelves, where documents were piled in neat stacks. She began dragging papers down and spreading them out on a desk, and she dug out reading glasses from her blue overalls. She was a frumpy middle-aged woman preparing to study, George thought, while armed soldiers stood around with weapons raised.

Julia was getting more agitated. 'Do not touch our work – do something, Josef, you coward!'

But Trojan was distracted too. 'Ernst?' He sounded bewildered, and spoke in German. 'It's you, isn't it?'

Another figure stepped forward from the rubble of the doorway. He wore a Wehrmacht uniform, and had his hands tied behind his back. 'Josef. I think I imagined we would never meet again…'

'Do stick to English, you fellows,' Mackie said laconically.

'Well, well,'Julia said sourly. 'It's a day of reunions.'

Trojan seemed outraged. 'What is the meaning of this? Why have you brought my brother here? If he is a prisoner of war he should be treated as such.'

'Like Ben Kamen?' George spat, and got another jolt from Julia.

'Isn't it obvious, Josef?' Julia said. 'He's here to make you dance to their tune.'

'Oh, I wouldn't put it quite like that,' Mackie murmured.

'Liar,' Julia said calmly. 'Ernst is a hostage, just like Sergeant Tanner here. You are a hypocrite, Captain. It's the one thing I've always despised most about the English. The sheer bloody hypocrisy, when we are the worst butchers of all.'

Mackie studied her. 'Do you really loathe yourself so much, madam? Is that what this is all about?'

Ernst said to his brother, 'Josef, even on this day of all days, you skulk in the ground with women and absurd machines. What would Father have said?'

Trojan looked hurt. 'I am trying to win the war. And cement the Reich's power so that it will truly last a thousand years – ten thousand! If you understood, you would see.'

But to George, he didn't sound as if he believed it himself, not any more.