Which cave would she choose? The first was shallow and narrow and slimy with anemones clinging beadily to the entrance. The second was long and deep and with a tall crack in the ceiling that stretched up into darkness. Some boy or other once told her the crack was built by a giant rock-spider that had tunnelled out a track to the cliff surface with its fangs, and although she knew it was nonsense, she had never been able to shake the image.

The third cave was called the Smuggler’s Cave because beyond a sterile pool of salt water there was a second chamber with a ledge like a narrow shelf, and there was a never-tested theory that if you climbed onto the ledge and clung to the wall, you could hide from the Revenue men and beat the tide and survive (cold and uncomfortable, but not actually drowned) until the waves receded and left you free to walk back out into the sunlight. The periwinkles clinging to the wall proved this story’s untruth, but the Smuggler’s Cave was the furthest away, and therefore the furthest from safety. She waded through the knee-deep pool without taking off her trainers and pulled herself, dripping and soggy, onto the rocky ledge.

Her hand reached automatically into her pocket for her phone, but she’d left it on the living room floor. She was used to filling idle fragments of time with idle fragments of activity. Now she had literally nothing to do but watch the remorseless progress of the tide and consider what she’d done.

Was this suicide? In the cold black silence it was hard to think. If she’d had longer to choose, there might have been another solution, but there had been no more time. And now it was too late. Her heart pounded with a strange excitement. What had she done?

The first eager waves rolled in through the entrance of the cave, edged with foamy lace. Her soaking clothes leached the warmth from her body, but she refused to take them off. Let the cold take her, let the water creep up her legs and turn her skin pale and wrinkled. Even if her father had come looking for her, he’d never get here before the tide came.

Then the darkness was pierced by a finger of light and a torrent of curses as someone waded, shivering, through the pool. She hadn’t thought it was possible to feel more frightened, but the bulky distorted outline coming towards her was a shape out of her darkest nightmares. Her father had found her. Her father had found her. Now they were going to die together and it would all be her fault. She cowered in terror.

“Alicia?” A familiar voice, not her father’s. “Alicia, is that you?”

“Finn?” She hardly recognised her own voice.

The torchlight shone right in her eyes so she couldn’t see his expression. “Jesus, it really is you. I thought it was, so I came to look – what on earth are you doing here? Can I sit down?”