'My God, Tom,' Mary said now. 'They know all about us.' She held up sheaves of paper. 'Even the simulations we did. Here is your 1938-war counter-history. And – oh my Lord – my Dunkirk study.'

Josef said, 'We are the SS. Do you imagine your work was immune to our intelligence? I must say that MI-14 in particular was very prone to leaks.'

'Actually,'Julia said, 'we found your studies useful. You kindly worked out the corresponding Godel trajectories for us. We used these ideas as rehearsals.'

'Rehearsals?'

'You do understand how the Loom works?'

'I believe we have a good idea,' Mackie said.

'Ben Kamen is our messenger, our sleeping child. We have used your solutions as exercises, using hypnotic, mnemonic and other techniques to force the information into his addled head, the Godel trajectories and the counter-historical mandates.'

Mary looked at Julia over her reading glasses. 'My God. You actually, um, loaded in my Dunkirk scenario?'

'And the 1938 study. Of course we never let him sleep until these were out of his short-term memory.'

Mary leafed through the papers on the desk beside her. 'And this is what you have sent back. Yes?' She produced a set of papers covered with diagrams, like engineering sketches. George squinted to see. Aircraft with wings like birds', submarines like metal fish. 'Weapons designs, sent into the past. And gunpowder. You're sent back a recipe for gunpowder.'

'We call it the Codex,' Julia said. 'Rather proud of our research, actually. Not easy coming up with weapons that would make sense to a grubby-arsed monk of the Dark Ages.'

Ernst was staring at his brother. 'What is this madness, Josef? Into whose hands did you hope to place these weapons?'

'Ah,' Mary said, and she produced another paper from the pile. 'That depends on the second of these missives, doesn't it, Standartenfuhrer? The Testament – which I now see,' she said, reading, 'was to go back into the head of a woman of the eleventh century. A wife of one of William the Conqueror's warriors, called Orm Egilsson. So that's who Eadgyth is. Wasn't Egilsson involved with an English priest called Sihtric, one of Harold's inner circle? So that's the way in.'

Julia frowned. 'You know a great deal about our work. Who were your spies?'

Mary shook her head. 'I didn't get this information from spies. I'm a historian, not a detective; I got all this from historical research. Whatever you have done has left traces in the past.'

'And are we too late, Mary?' Mackie asked grimly. He glanced around. 'Is history changing around us, because of these criminals?'

Julia went straight on the attack. 'Criminals? You patronising slug, Mackie, Captain, Royal Navy. Men like you have always disgusted me. You abuse the Party. You bleat about our treatment of the Jews. But who devised the blood libel? The English. Who expelled Jews in the thirteenth century? The English. Who set up concentration camps in Africa? The English. And you Americans are no better, Wooler. You bleat about our racial laws, but there are marital segregation laws in your southern states which the Party used as a model for its Aryan-Jewish laws. Everything Hitler has done is in the context of history – your history.'

Mackie listened to this, stone-faced. 'I really do think we should get you to a bump-feeler, my dear.'

'Do not speak to me!' she yelled, a hysterical edge to her voice.

Gary glared at Julia. 'Why is this Nazi woman keeping us talking? There's something wrong here-'

And suddenly George saw Gary was right. This was all a performance, he knew Julia well enough to see that. He glanced around. Ben, in the tank, was still stirring, his eyelids lifting like heavy curtains. He was fighting the drugs.

George said quickly, 'Listen. Gary's right. She's stalling. She sent the first lot back, the Codex. I heard her. But the second lot, this Testament, she loaded it into him but-'

The butt of Julia's pistol slammed down on the back of his skull. It felt as if his head exploded. He was on his knees, on the floor, but he was conscious. 'Ben – in the tank – keep him awake-'

It all kicked off.

XVII

Josef Trojan made a rush at the tank. But his brother blocked him, arms behind his back, getting in his way bodily. Then the British soldier, Willis, the blond one, jumped on them both.

Julia screamed her frustration, swinging her silver pistol wildly.

Gary charged her. She aimed her pistol. She fired.

George saw it clearly. Gary lumbered on, his legs still working as if by reflex, his limbs uncoordinated, his head lolling. But his forehead was a shattered mass of blood and bone. He tumbled into Julia, knocking her down. George was pushed sideways; on his back, stunned, handcuffed, he could barely move.

Mary fell on the body of her son, and the woman who had killed him. Her face was contorted, a mask of grief and rage. She clawed at Julia's throat, her hair coming loose from its tie, a cloud of grey around her twisted face.

Mackie dragged her away. He grabbed Julia's hand and crushed it, making her scream, until he had forced the silver pistol out of her fingers. He looked across at George. 'Sergeant. Help me. Hold this woman.'

. George willed himself up onto his elbows. His head rang, and his vision was blurring. But he rolled over and lay on top of Julia. Mackie dug keys out of Julia's pocket and released George from his cuffs. His hands free, George got her by her wrists, his heavy arse pinning her legs. She stared up at him, stunned, the bloody marks of Mary's hands on her throat.

Mackie pulled Mary to her feet. 'Mary. Mary! Listen to me. Listen. I know it's hard, my God. But you have to help me. The job's not done yet. The mission.'

Slowly she replied, 'The mission.'

'The Loom. You heard what George said. God, how can I have been so stupid? She was stalling – why didn't I see it? They didn't finish the job. Fiveash sent back the Codex. But she's still in the middle of sending back Eadgyth's Testament. We still have a chance.'

'But Gary, look at him, he's not even got his face covered-'

'Mary, we have to make his loss worthwhile.'

She pulled away from him. 'Don't you speak to me like that, you manipulative prick.'

He held up his hands. 'All right. I deserved that. But, Mary, for now – please.' He began to tinker with the bank of controls beside the tank. 'What if we stop the supply of opiates? Fiveash, which is the switch?'

'Too late for that,'Julia said, pinned on her back, her mouth twisted into a sneer. 'Too late! The Jew will be under in a minute, and everything will change.'

Mackie looked around. 'Trojan? Is she right?'

'I am afraid so,' said Josef Trojan.

'Plan B,' Mary whispered. 'Turn Columbus west. Not east.'

'Yes.' Mackie said. 'That's it. Good. Good, Mary. Come on, work with me now. We prepared for this eventuality, didn't we? If you can feed him your alternate version of the Testament, maybe that will be enough. Trojan, is this a microphone? Can Ben hear us? You can do it, Mary. Come on. Speak into his ear as he falls asleep. Do you remember what you worked out? The Aztec feathered serpent, the Chinese dragon-'

'They could just kill him. Kill the little fucker. But that hasn't occurred to them, has it?' Julia whispered this to George, as once she had whispered erotic promises.

He pinned her down harder. 'Shut up. For the last time, shut up.' He held his face over hers, close, as if he might kiss her. But a drop of blood from the wound she had inflicted rolled over his scalp and splashed on her cheek.

Mary lowered her head to the microphone. The body of her son was sprawled at her feet, and George could see how she was drawn to him, as if by elastic cables. But she spoke into the mike, improvising. 'Egilsson. Orm Egilsson. Can you hear me? Are you there? Are you there, Orm Egilsson? Orm Egilsson! Listen to what I have to tell you. Listen, and remember, and let your sons and their sons remember too…'