'That's common enough. The nearest shelter is under the castle. Come on, I'll take you.' She held Mary's arm and led her quite confidently through the dark. But the girl limped as she walked.

Mary said, 'You're hurt yourself.'

'Kicked out an incendiary. Got a bit burned. Feel foolish, actually. I'll live.'

Mary was an independent sort, but she was happy to let the girl take charge. 'Thank you, um-'

'Doris Keeler. Just call me Doris. Are you American?'

'Yeah. Mary Wooler. Good to meet you, Doris.'

'I've got an aunt in America. Just visiting, are you?'

'Sort of.'

'Well, you picked the right summer to visit England. Here we are.' The castle wall loomed before them, and they hurried through an arched doorway. Doris shone her torch on a sign, white on black, with a large 'S', an arrow, and the word 'SHELTER'. They hurried down a narrow staircase.

Mary found herself in a tunnel-like vault, with walls of brickwork. The light was dim, coming from electric lamps hung roughly on the walls, but there was a stack of candles and what looked like old-fashioned oil lamps standing by. Doris snapped off her torch and took off her helmet, revealing brown hair tied back into a tight bun. Her features were regular, strong rather than pretty; she looked competent.

The vault was already crowded, the people packed in rows on the floor like sardines in a tin, mostly women, children and older folk, and a few men of service age. They were settling in for the night, Mary saw. There were beds that looked like official provision, but they had already been occupied. Otherwise people had brought down heaps of blankets and deckchairs and bits of carpet, and were making up nests under the vault's curving walls.

The place was quite organised, with trestle tables bearing tea urns manned by WVS volunteers. An oil stove was burning, and a cooking smell filled the muggy air. One section of the vault had been fenced off by a couple of blankets; from the smell Mary guessed that the privy was back there.

Doris led Mary to a first-aid table, where mothers sat with sick children in their arms. Mary protested, but a volunteer here, a stern middle-aged woman, took a brisk look at her knee, fingering the joint – 'a bit of bruising, that's all there is to that' – and washed her scraped hand, dabbed it with antiseptic and gave her a bit of bandage. Doris said nothing about the injury to her own foot, and Mary didn't prompt her.

Doris found a bit of wall where they were able to sit, their backs to the brickwork. She fetched Mary a cup of tea, and set her helmet down on the floor between her crossed legs. They were surrounded by people, a warm fug of wriggling bodies, a stale smell of woollen clothing, a murmur of conversation. Mothers tucked in their children, three or four to a bed. A lot of people were reading, papers and Penguin paperbacks. One old man who looked like a rabbi was reading a leather-backed holy book. It was all quite cosy, and few people seemed afraid; it had all become a routine, Mary supposed. But she could hear the deep rumble of aircraft engines, the distant slam of bombs, and the hammering shudder of the ack-ack fire. There was nothing gentle about the night.

'I needed a break,' Doris said, sipping her own tea. 'It's been a long night already.'

'It's all very organised,' Mary observed.

'Wasn't like this in the beginning. My word, after a night down here you could have sliced the air up and carried it out.'

'But, you know, speaking as an outsider I'm impressed by the way the Brits have adapted. Coping the way you do.' All this achieved by a nation, repelled by the industrialised slaughter of the Great War, that had never wanted this conflict.

Doris sniffed. 'Well, a bit of common sense and an ounce of courage get you a long way in my experience. Actually we haven't been hit so hard, not yet.'

'No. Not like the coastal towns. I've been staying in Hastings. The people there shelter in caves.'

'Really? Well, the coast's been getting it, they say, and the airfields and the like. Softening us up before old Hitler invades. So they say.'

'I don't think they'll invade.'

'No. They don't need to – that's what's said. They can just starve us out, can't they, with their U-boats in the Atlantic?'

'Do you have family? A husband?'

Doris eyed her; she'd evidently asked an awkward question. 'Well, my husband was with the BEF. He didn't come back from France.'

'I'm sorry.'

'I got a Red Cross postcard. He was in a POW camp outside Paris. They say they're now being shipped further east, off into Germany, to be used for labour.' She laughed. 'I suppose it takes even the Germans a bit of time to move a whole captive army, four hundred thousand men.'

Mary told her about her son. 'I suppose I was lucky. Gary came back in one piece, more or less. He'll recover soon.'

'And he wants to fight again?'

'Oh, yes.'

'It's all a frightful mess, isn't it? I miss my Bob, of course, and so does Jennifer. I don't suppose we'll see him before this beastly war is done.'

'Jennifer?'

'My little girl.' She opened her coat and dug out a photo, of a sunny pre-war day, showing Doris herself, a smiling, prematurely bald young man, and a little girl of five or six.

'She's pretty. Where is she now?'

'Well, I have that aunt in America. Somewhere called Kentucky, she lives. We had a bit of money saved up before the war, and we decided we didn't want Jenny off in the country somewhere, but with family. So we bought her passage. She's up in Liverpool at the moment, but she's supposed to sail next month on the City of Benares. She'll be safe in America, won't she? I'm afraid I don't know anything about your country, nothing but what's in the movies.'

'People are kind. Just like here. I'm sure she'll be fine.'

'Well, after she went off I thought I may as well do something useful, and I joined the ARP. But I miss her ever so much.' She was absent for a moment, and then she deliberately brightened, as if remembering to do her job. 'So what are you doing here in England?'

'Actually I was here before the war. I'm a historian; I was researching aspects of the late medieval. When the war came I stayed on, but I'm working as a stringer for a paper in Boston.'

'A what?'

'A correspondent. But actually I'm here in Colchester to do a bit of historical research. I'm following up a document somebody gave me.' It had been Ben Kamen, the young Austrian Jew who had befriended Gary. 'It concerns the Emperor Claudius. Colchester was a great Roman centre – a military garrison, just like it is now. But I've found my way to the archive of a monastery outside the town, where a medieval monk called Geoffrey Cotesford lived towards the end of his life. Funnily enough Cotesford knew a Wooler, who was maybe one of my husband's ancestors… Oh. I'm sorry.'

Doris smiled. 'Do I look a bit lost? That's rude of me. I don't know much history. Who's this Claude?'

'Claudius. The Roman emperor who conquered Britain.'

'Wasn't that Julius Caesar?'

'No. Long story.'

'I don't even know anything about this blooming great castle we're sitting under. The Normans built this, didn't they? William the Conqueror and his lot.'

'Well, yes. But that's a long story too. This vault was built by the Romans, but it's not really a vault. Colchester used to be the capital of the ancient Britons. After the Romans conquered it they built a huge temple to Claudius, right on this spot. This vault is actually the foundation of the temple, like a big concrete raft.'

'So the Romans came, then the Normans, and now here we are hiding under it all from the Germans.'

'Well, that's history for you.'

The folk in the shelter were growing quiet now, the children shedding their excitement and settling down to sleep, some of the adults talking in soft murmurs. In the shadows of one corner near the WVS table, Mary saw one couple with their mouths locked together in passion.