'it's december!'

'ok, no red bathing suits this time. that'll have to wait till i can take you to the conewago grove lake. anyway, it doesn't matter. we have to do it for karolina.'

i was brutal. i didn't hit ro?a. i didn't touch her. but i was brutal.

'karolina was gassed instead of me, she took my place, she took my number, but she didn't do it for me, ro?yczka, and you know it. she did it for you. she did it so i could get you out of ravensbruck and you could tell the world what they did to you - what they did to karolina. she wasn't as permanently damaged as you, but she still got a paper cone full of bacteria sewn into her leg and ended up so swollen with infection she couldn't walk for eight months -'

ro?a was clenching her fists.

'i know what they did to karolina,' i went on mercilessly. 'i know exactly what they did to every single one of the rabbits. it's all been recorded by the people you work for, and maybe you haven't read the specific reports, but i have, because they're all part of dr alexander's evidence. karolina could have told the world herself. she'd be making newsreels about it - people would be using her work as evidence too! she could have left me to be gassed with the rest of my transport, and she'd have stood up there in front of that tribunal and showed everybody what happened. but you didn't. and i'm not blaming you for that, but you are darned well flying to the beach with me. because karolina was going to and she's dead and you're coming along in her place.'

by the time i'd finished, ro?a was crouched in a heap on the floor of our room, bent over her knees with her face in her hands. all i could see of her were her round shoulders in their sensible grey wool and the short, fluffy waves of caramel-gold perm. but she wasn't crying; her shoulders weren't shaking. she was thinking.

after a few seconds, when she was pretty sure i'd finished, she sat up and looked me in the eye.

'the ravensbruck trial in hamburg's not over yet,' she said. 'tell the world yourself, rose justice! i know, you've got all these poems published and you're doing a story for your magazine, big damn deal. you sit in your room all alone at your typewriter, with no one watching if it makes you cry, and you take it to the post office and no one even knows what you're sending. how hard is that to do? i could do that. i've done that. my written testimony is part of the lund files too, you know. no. if you want me to go flying with you for karolina, you will damn well go to hamburg for karolina.'

it was my turn to feel like i'd been punched in the stomach and she saw it in my face. ro?a let out one of her familiar, maniacal cackles. 'you won't even have to take your clothes off!'

'i've already said no,' i said faintly.

'bah. bribe the judges.'

which is exactly what anna had said.

and suddenly it became like so many decisions i'd made during the war: i didn't have a choice. i had to do it whether i wanted to or not. not just for karolina, who was dead, but also for anna, who was still alive and had no one to defend her.

you only fly straight and level in balance.

anna and ro?a are the opposing forces that perfectly balance each other to keep me in the air.

it was harder to get the words out this time than the easy promise i'd made to anna in the washroom in the palace of justice.

'you've got a deal,' i gasped.

ro?a and i got up at the crack of dawn and shared a car with a couple of bbc reporters who were heading out that day with a lot of equipment. they wouldn't let us help them carry anything, and one of them actually went out of his way to take ro?a's arm and help her across the churned slush to the makeshift operations building at the airfield, which meant he had to do two trips - but sometimes you have to just give up being independent and graciously accept the kindness that's offered you. and anyway, this was without a doubt the sorriest excuse for an airfield i have ever seen, even counting the one they knocked up at camp los angeles right after reims was liberated. i guess that is our own fault for bombing nuremberg's real airfield to smithereens.

i'm painting a scene of gloom, but in fact it was a glorious, glorious day - crystal clear and breezy. there had been another inch or so of snow overnight so folks were frantically clearing a very narrow path up the runway. chuck produced flight suits for us, which for some reason made ro?a laugh her head off - her real laugh, which i'd hardly ever heard in all the time i'd known her, bubbly as champagne. 'are we going to go skiing?' she asked.

'why skiing?'

'my mother used to put me in this awful snowsuit - baggy legs just like this, four sizes too big for me, and it was purple. she'd roll up the legs and hold them in place with rubber bands.'

i'd never heard her talk about her mother either.

there weren't any passenger seats in the plane - just benches along one side and plenty of room for cargo. ro?a clutched my hand as we approached the plane. dakotas are big.

'don't worry!' i told her. 'it's like getting in a bus. you've never flown in daylight, but it really is beautiful in the air. if you close your eyes while we're taking off -' i stopped abruptly, remembering polly's reaction to the same words.

'i'm not a baby,' ro?a snapped, holding her head up, her china doll cheeks rosy with the brisk december wind. 'i said i'd do it and i'm doing it with my eyes open. are you going to close your eyes in hamburg?'

'you really are the world's worst pain in the neck,' i complained. but my heart ached for her bravery.

i hadn't actually thought about our route when i'd set up the trip. i'd thought we'd see a lot of bomb-damaged cities - i'd seen so much bomb damage from the air. i'd wondered, briefly, when i first got the idea of taking ro?a flying, if i could find someone who'd fly us over ravensbruck. after i'd hung up talking to chuck the night before, i'd had to go hide in the ladies' powder room and sob for a while. oh, karolina.

but i hadn't actually realised that this flight was going to give both me and ro?a our first sight of the alps.

the first part of the trip was mostly just snowy fields and forest, gleaming swathes of white and increasingly huge tracts of black-green pine. then, as we made our way further south, the landscape grew rockier and steeper and we could see the crags of the austrian alps climbing ahead of us. they don't pressurise the c-47s and they didn't have oxygen hooked up in the back, so the highest we flew was about 10,000 feet. that meant that there were moments when we were flying between mountain peaks. grossglockner, austria's highest mountain, was blinding in the midwinter's day sunlight, glittering white and gold and rising 2,000 feet higher than we were flying. it was like flying over another planet - over another world, oz or wonderland or the moon.

honestly - there were moments, many of them, when we were between peaks, with snowbound crags and rock all around us, when ro?a really was so enchanted that she forgot to be scared. we were surrounded, as far as we could see, by our world's sheer unspoiled majesty. it was unspeakably, indescribably beautiful. it wasn't even barren. we could see glimpses of valleys and farms; there far below a touch of green where it hadn't snowed yet; there a river; there a fairy-tale village.

we were both pressed to the windows on opposite sides of the empty cargo plane.

'did you know?' ro?a gasped. 'did you know it would look like this?'

'i didn't even think about it! we just got lucky!'

'even without the beach it is worth it. i won't mind so much getting work sewing on laundry tags if i remind myself about this.'

i wasn't sure how to respond to that driblet of self-pity.

i asked cautiously, 'ro?a, what are you doing for christmas?'

'there's a party at the institute. it was fun last year - poles and swedes all mixed up. i don't know how much fun it'll be this year though, since the funding is finished and nobody has work in 1947.'

'do you actually have a real possibility of spending the next few years sewing on laundry tags?'

'no. i haven't looked for that job yet.'

'for the love of pete.'

no wonder she seemed so beaten.

'what are you doing for christmas, rose?' she asked. 'are you going to pennsylvania?'

'how could i? it takes a week. i'd be on the boat on christmas day!'

ro?a gave one of her raucous hoots of laughter. 'fly. did you go last year?'

'no, i had an awful christmas with my aunt edie and uncle roger in england. i did nothing but cry all christmas day. it was worse than the year before. all of you were gone. and the next day, the 26th, they have this big annual party and there were about a hundred people in the house and i just felt like a freak. so this year -'

throughout this entire conversation we'd had our backs turned to each other, standing on opposite sides of the bowels of the plane, glued to the small windows. there was frost on the rivets and the grey ribs of the plane's interior walls. but outside it was fairyland.

i said, 'ro?a, come back to scotland with me on monday. i'm going to stay with my friend maddie for a week with her husband's family. maddie told me to bring my friends. i know i promised you the hotel hershey, but i swear that craig castle will be just as nice.'

'oh, how could i!'

'easy! the place is always full of orphans and soldiers with missing arms - they won't notice you. i mean -'

she giggled evilly. 'the soldiers will, i bet.'

'yes, they definitely will, but i meant that one more -'

'- one more crippled orphan.'

'oh, stop. you know what i mean.' i drew a shaking breath. 'and anyway, we are in the same family. that won't change.'

ahead of us, the mountains dropped away and the black-green forest gave way to duller and brighter green ahead. the italian fields were tiny and patchwork - you could tell you were in another country. far, far away on the horizon was an astonishing stripe of sapphire that we knew, but couldn't quite believe, must be the adriatic sea.

'there is a medical school at the university in edinburgh which they teach entirely in polish,' i said. 'they started it in the middle of the war. i could take you to meet my tutor and we could ask about it. you could do your high school exams in edinburgh and maybe try the university course next fall -'

'we could share an apartment?'

'of course! and ro?a -' i choked a little, because it felt like we were making up another rescue fantasy. it felt like we couldn't possibly be planning something that would really happen. 'ro?a, we can write our book.'