‘Well, that could be impressive, too, you know.’

‘I’m not going to do it, Rose. They’ve got four smart, educated grown-ups to show off and they don’t need my testimony and I’m not going to do it.’

I held on to her tightly while she calmed down a little.

‘Will you tell Dr Alexander for me?’ she begged.

I could see why she didn’t want to do that herself.

The wily Ravensbrück prisoner in me rose to the surface.

‘I’ll tell him for you,’ I agreed. ‘But only if you sit with me and watch the trial.’

‘You bitch,’ she snapped automatically, and I was so relieved to hear her being nasty. But she didn’t act like she was mad at me. She hugged me tightly round the waist, snuggling all her weight against me.

She was so much heavier than I expected. No lift balancing her life at all.

3. Drag

Dr Alexander took it very well, considering how early it was and that I had to interrupt him in his office right before the session started so I could catch him privately, and this was the last day before the Christmas recess. He is such a kind man.

‘I’m not surprised,’ he admitted. ‘I thought someone might back out, and I’m glad it’s Róża. She’s a volatile witness. She’s different from the others.’

‘Different how?’

‘She isn’t finished. She has no sense of who she is. The others knew that before the war started – but how old was Róża when she went to prison, fourteen? Sixteen when she underwent the first experiment? She grew up in Ravensbrück. In a way, she’s still there.’

I knew exactly what he meant. There wasn’t any part of Róża that wasn’t connected to Ravensbrück, even her work, even the parts of her body that had escaped experimentation – she hadn’t started her period until she was eighteen, after the war was over.

It is true that Ravensbrück shaped me – whatever I would have been without it interfering, I am someone else now. On the simplest level, I don’t think I would be in Scotland or in medicine. But Ravensbrück doesn’t define me. I had a lot of ‘being Rose’ to cling to when I landed there – I was a pilot, I was a poet, I was a Girl Scout, I was part of a family, I was the captain of the Mount Jericho High School County Champion Girls’ Varsity basketball team, and I still bore traces of all these things even in the concentration camp. I wore my Air Transport Auxiliary USA flash on my shoulder and identified the aircraft that flew overhead, so we could guess at how the Americans or the Soviets were advancing. I was given jobs only a tall girl could do; I taught my companions Scout songs and learned theirs; I produced more poetry in six months than I’d ever produced in my life, most of it in my head. And I was part of a family – Lisette, Irina, Karolina, Róża.

Róża was part of my family. But her own real family had all been killed before she’d even arrived at Ravensbrück. I knew mine were safe. That made a difference, too. Róża’s Camp Family was her only family.

When I told anyone at the camp who I was, I’d say, ‘I’m Rose Justice. I’m a pilot.’

When Róża first told me who she was, she’d said, ‘I’m Polish Political Prisoner 7705. I’m a Rabbit.’

When you’re flying, the changing balance of lift and weight pulls you up or down. But another pair of forces pulls you forwards or backwards through the air: thrust and drag. Thrust is the power that pulls the kite forward – you run with it to get it up in the air. You have to have thrust to create lift. Drag is there because your kite’s surfaces push against the air and slow the kite down. Drag doesn’t pull you out of the sky; it makes you fly more slowly.

For the most part, Room 600 in the Palace of Justice, the Doctors’ Trial courtroom, looked just like you imagine any courtroom – actually, it looked spanking new, with its wood panels gleaming with varnish, and modern lighting installed in the ceiling. That was all done last year just before the IMT, the International Military Tribunal. The four American judges were all wearing new robes flown there specially from Washington DC. But the outstanding feature of the courtroom was that it was entirely snarled in telephone and electronic cables for the simultaneous translations, everybody caught in a huge black spider’s web. Everyone was connected by this web – defendants, witnesses, lawyers, judges, observers, reporters and, of course, the panel of translators themselves – everybody had his or her head plugged into this amazing machine. You could tell right away who’d been here before and who was here for the first time by their nonchalant or inept use of the headphones.

Talk about drag! You were so dependent. Also, it was easy to see why people just stopped listening when Madame Vaillant-Couturier was telling them about the gas chambers at Auschwitz. It was like turning off the radio. You can’t bear to listen? Just pull the headphones off.

Róża, who understands English and Polish and German, didn’t need headphones.

We sat in the gallery to watch, just in front of one of the film crews. We were surrounded by an intense crowd of German medical students my age who were frantically taking notes. Róża perched ramrod straight on the edge of her seat. She gripped the sides of her chair. I don’t know what she was thinking, but she looked like a fury. Her face was set in a sneer and her eyes were burning. She didn’t watch her friends giving evidence; her gaze was locked on the defendants, the twenty-two Nazi men and one woman.

Dr Alexander’s evidence and the questioning of the Rabbits took the entire day, and no one else dared question them. The presiding judge, Walter B Beals, would ask if the defence wanted to cross-examine a witness and there would be flat silence. One of Jadviga’s scars had been inflamed that whole week and she stood there anyway, still in pain, telling about how they tied her down in the Bunker.

How you knew they were going to operate on you because the first thing they did was shave your legs.

Telling how Fischer had smoked cigarettes between operations without bothering to change his gloves.

How Oberheuser would make the girls stand in line, hopping on one uninjured leg to get the filthy bandages changed on the other leg, and then instead of changing them she’d tell them to come back the next day.

How sometimes, if you fought, they’d blindfold you for the operation, or wrap your head in a blanket.

About the woman guard who’d said, ‘They must be made to suffer before they’re executed.’

Fischer wouldn’t look at Jadviga. He couldn’t look at any of them. He’d done most of the operations himself, under Gebhardt’s instruction.

By the time little Maria finished her testimony at the end of the day, it sounded like there wasn’t anyone breathing anywhere in the crowded, wire-webbed room. Maria is only a couple of years older than me. She’d had muscle peeled away from her leg right down to the bone – half her leg was gone. She looked very vulnerable up on the raised platform with her back to the court, in a stylish new dress but holding her skirt bunched up around her thighs, barefoot, barelegged. Dr Alexander did a juggling act with his notes and his microphone while he pointed out how they’d torn apart her leg, but all I could do was stare at the tendrils of hair curling at the nape of Maria’s bare neck, escaping from where her hair was elegantly pinned up.

No wonder Róża’s backed out of this, was all I could think. Next to me, Róża didn’t stop gripping the sides of her chair.

I followed her gaze to the defendants, tied up in their telephone wires. Only Fischer looked remotely unhappy, his forehead resting against his fist. The others just sat staring straight ahead as though they were made of stone.

Then I looked around the room below us. There really weren’t very many women at all, and when I found one in the crowd, I’d stare at her for a moment, wondering who she was – someone’s secretary? A German doctor’s wife? A reporter or photographer?

In front of us, a girl with straight dark hair clipped back in a flat pony tail with a metal barrette was looking back at me – waiting for me to meet her cool green gaze. Hers was the only face turned upwards towards the gallery and not towards the witness stand. It was Anna.

She’d seen me and remembered me. She didn’t smile – it would have been weird for anyone to be smiling at that point, even in greeting. She gave me a brief, curt nod.

I nodded back.

She hesitated a moment. Then she rubbed her hands together deliberately, turning her palms over each other and rubbing the backs of her knuckles, briefly miming washing her hands. Just for a second. I knew exactly what she meant.

Meet me in the washroom.

When the day’s session was over, the last session before the Christmas recess, we gathered in one of the vast ornate lobbies, shaking hands with people and congratulating Dr Alexander on his moving presentation. Vladyslava and Jadviga and Maria and the other Maria got their photographs taken. Some of the photographers wanted to include me and Róża too, but I refused because I wasn’t a Rabbit. When Vladyslava insisted Róża join them, it was the perfect time for me to disappear for a few minutes.

‘Powder room,’ I told Róża. ‘Back in a minute! You all look beautiful – I hope they slap you on the front page of the New York Times!’

Anna was waiting for me, leaning against the sink and smoking – exactly the way I’d left her in the Revier in Ravensbrück not quite two years ago.

‘Häftling Einundfünfzigtausendvierhundertachtundneunzig!’ she rapped out. Prisoner 51498!

I don’t think I’ve ever been hit so hard by a handful of words.

It was probably the first thing that came into her head when she saw me – an exclamation of surprise, not a command. She usually did call me by my number because she was supposed to. But to hear my number barked at me in German like that was more than my brain could react to sensibly. I snapped to attention, head up and staring straight ahead, arms straight at my sides.

There was another woman in the room, an old woman sitting in the corner with a bundle of knitting, who stood up in alarm when I made my dramatic entrance. I realised she was the attendant for the ladies’ restroom, and I relaxed and kind of melted against the door frame, hanging on to it with one shaking hand as though I had missed my footing. The way a cat washes itself when you catch it doing something clumsy, pretending you never saw that.

I recovered myself and startled Anna back by throwing my arms round her. She held the cigarette away and stiffly returned my ridiculously enthusiastic embrace with her other arm.

‘Calm down, kid. Sorry! It slipped out – like being slapped in the face, isn’t it? Gives you power.’

She was still fluent enough in American slang to sound like a gangster. I guess she’d been chatting a lot with the soldiers. The attendant sat down and picked up her knitting again with a hmph, ignoring us now that we seemed to be friends.

‘Oh, Anna!’ I felt tearful. I’d really thought she was dead. She was playing her part in the trial with complete calm though, so I tried to keep my voice from shaking too. ‘What are you doing here, Anna?’