‘Come and see.’

‘Why can’t you just tell me?’

‘Because I think you’ll like it.’

He got up, giving an exasperated sigh that would have made any self-respecting teenager proud. ‘What is it?’ he asked, standing by her. His expression changed as he caught sight of what she was staring at. Perhaps a hundred feet inland, a crescent of blue could be glimpsed through a crater. ‘That’s the sea.’

‘Right?’ She grinned.

‘Do you think that’s . . .?’ He looked up at her, mouth agape. ‘The hidden beach?’

She winked at him. In all their miserable resentment, they had both completely forgotten about it. ‘There’s only one way to find out. Come on, let’s find the way in.’

Together they scrambled down the incline.

‘Right, you go first,’ she said, pushing him ahead of her.

‘Why me?’

‘Because you’re faster, and if this is where Dr No keeps his sub-atomic testing facility, then I’m going to need a head start for getting out of here.’

Linus laughed, shooting her a look that wouldn’t have been quite so wry a year ago. He was growing up.

They climbed, ran and scrambled over the rocks and through the trees, the sea at their backs, until the crater suddenly opened up at their feet. Absolutely huge, perhaps fifty metres across, it was an almost perfect circle blown in the rocks. The force of the bomb had set the beach ten metres below ground, the grooved granite walls scooping away beneath them. Three quarters of the basin floor was covered by sea, with a shallow beach that could only catch the sun through the middle of the day.

‘How do we get down there?’ Linus asked in amazement.

‘Maybe we don’t,’ Bell said, puzzled. ‘Your mamma didn’t say anything about swimming down there. Only that it was there.’

‘But I want to swim down there.’

Bell rolled her eyes. Of course he did. Now he wanted to swim. ‘Well, it’s too far to jump down, and we’re definitely not going down if we don’t know if we can get back up again,’ she said, seeing the sharp concave angle at which the rocks were cut away.

‘There has to be a way down,’ Linus murmured, beginning to walk around the perimeter. ‘Maybe there’s a rope.’

‘Oh yeah, because I could definitely get myself back up again on that!’ Bell guffawed.

‘Look!’ He pointed to something halfway round. In one spot, perhaps a seam of thicker rock, the wall hadn’t been blown back quite as far as elsewhere and the cliff kicked into the basin, like a stray pleat. A narrow channel ran down the centre of it, rainwater running through like a rill. It was about a foot’s width – depending on the foot.

‘Linus, those are not steps,’ she protested as he tore ahead and skittered down it like a mountain goat. ‘Linus!’ she called, seeing how he held his arms out wide, stepping confidently, jumping onto the sand a moment later.