Sleeping was like falling into a series of shallow black holes; I woke over and over again, yanked up into consciousness by the wind tearing at the tiles on the roof, or the blast of waves pounding into the cliff face below my bed. When I was awake, I thought about the faces of the people who had turned against Mutti in the courtroom – people who needed her to be the enemy so that they could do something with all that anger and fear and hate they had inside. I thought about the Nazis creeping closer and closer to us through the darkness; I thought about a U-boat hanging there in the murky-green gloom, far below the churning surface of the Channel. All through that long, stormy, miserable night, visions of the Wyrm writhed wildly in my mind.

‘Are you all right, Pet? Pet?’

My sister’s voice. Her hand on my shoulder, shaking me awake.

It’s not real, then – the sea-dragon squeezing and scraping its way up the lighthouse steps, the hiss of its rotten-fish breath, hungry jaws filled with row after row of teeth . . . I don’t have to hide any more – it’s not coming for me. It’s not real . . .

‘Pet!’

‘Uh?’ My breathing was quick, dizzy. My pillow felt wet under my cheek.

‘I think you were having that nightmare, Pet. That one you used to have when you were little. You were sort of . . .’

‘I was what?’

‘Whimpering.’

I sat up in bed. Our room was still dark, the ugly blackout curtains drawn tightly together. ‘Is it morning?’

‘It’s early. Five o’clock, I think.’

‘Did I wake you?’

‘I was awake anyway.’

I squinted at the dim outline of my sister. ‘Are you dressed, Mags?’ She didn’t appear to be wearing her usual striped pyjamas.

‘Yes. I’m going out. I’ve had an idea.’

‘What?’

‘If Mutti didn’t do those drawings,’ she whispered, ‘then someone else did. And if we can find out who the real spy is, we’ll be able to prove Mutti is innocent. Come with me, Pet.’

I sat there in the darkness. The last of the storm was over us now, and rain spattered rhythmically on the window.

‘Right now?’ My nightmare had left me shaken and frightened – I didn’t think I’d be able to move.

But Mags was not afraid at all. ‘Come on, Petra,’ she said. ‘For Mutti.’