Pa woke me before dawn the next morning. He didn’t mean to, but I heard the floorboard sigh as he came past our room. Mags was still fast asleep.

‘It’s all right,’ he whispered. ‘Don’t get up, Pet. I’m just going out in the boat for the day. I’ll be back tonight.’

Had he forgotten that I was there when he said he would take the lifeboat to Dunkirk? Perhaps he wanted to convince me that what he was doing was not dangerous at all – just a spot of fishing on an early summer’s day. Or perhaps he was trying to convince himself.

‘Take care, please, Pet,’ Pa said. ‘Look after the lighthouse, and look after that stubborn sister of yours too. Remember to go straight into the cellar if you hear the air-raid siren or planes overhead.’

‘Yes, Pa,’ I said.

‘Promise me.’

‘I promise.’

I wanted to reach out to him with both arms like I did when I was tiny. I wanted him to scoop me up so I could tuck my knees against his chest and bury my face in his shoulder. I couldn’t bear the thought of him going so far away, sailing straight into the clutches of Hitler’s army. And I couldn’t bear the thought of him coming home, only to turn himself in at the police station as a traitor. I had hardly slept a wink that night. Pa, the voice in my head whispered. Pa is the traitor . . . And then that dreadful headline again – TRAITORS TO BE HANGED . . .

‘I’ll see you tonight, then, my darling,’ he said, bending over to kiss me on the forehead.

The floorboard creaked as he turned away, and after a few seconds I heard the kitchen door open and close.

I shut my eyes and tried to get back to sleep.

I don’t know how long I lay there, my tired eyelids flickering in the gloom, but eventually I gave up on sleep altogether, threw back the blanket and went over to my sister’s bed.

‘Mags,’ I whispered. I don’t know what I was going to say to her, I just knew I couldn’t bear to be alone in the darkness any more. Should I tell her about Pa, about what I had heard through the speaking tube? I sat down on the edge of her bed and touched the shoulder-shaped lump of blanket. ‘Mags . . . ?’

But there was no shoulder beneath my hand, there was only blanket and pillow.

Mags wasn’t there.

It was a hideous moment, like biting into an apple that turns out to be soft and rotten inside. I pulled the blanket right back, just to be sure, and there on her bedsheet was a note addressed to me:

Pet,