Most of all, thank you to my amazing husband Tony for believing in me so entirely and supporting me so generously.

For big sisters and little brothers everywhere.

Chapter One: 1978

On this blazing afternoon the beach is home to both death and beauty, hiding its savage nature beneath a hot white welcome almost too bright for the eyes to bear. The retreating ocean has left tigery ripples in the bronze sand, and families with coloured windbreaks perch on the surface. Close to the top of the beach, billowy dunes bear witness to the power of the tide when it pours in, but now the waves are churning froth in the far distance and the dry sand dances in the wind. The children drop their buckets and stare in disbelief.

“What do you think?” their father asks.

“Struck dumb,” says their mother, ruffling her son’s hair. Her daughter, taller and older, frowns and pulls restlessly at the thin brown straps of her swimsuit. “Ava, will you leave those straps? They’re fine.”

“What shall we do first?” Their father looks around for a spot to settle. He selects a patch of sand, hesitates, walks on a few paces, pauses again, takes three steps more. The beach’s scope is so vast – a bite from the black cliffs, taken by a mouth nearly two miles wide – that choosing any particular spot seems arbitrary. “Want to build a sandcastle? Dig a hole? Explore the caves?”

His daughter turns her frown towards him.

“I don’t think we should go in the caves, Dad.”

“Why not?”

“That sign, remember? And the tide?”

“Those signs are just to cover themselves,” her father says. “They wouldn’t leave them open if they were dangerous.”

Ava looks disbelieving, but chooses to stay silent.

“So. What’s it going to be, kids? Who fancies going caving? Come on, Finn, you’ll love it.”

“Can we run?” His son, who has been scrunching his toes into the sand and studying the results with interest, looks up eagerly, bright black eyes beneath thick lashes. His skin is already turning golden.

“Well, I suppose, but wouldn’t you rather… ”

“Come on!” Ava seizes her brother’s hand and they charge off, roaring with delight, bare feet beating against the sand, the girl’s long brown hair flying, the boy’s black curls leaping. Their parents begin to claim their patch. The father hammers the windbreak with a rubber mallet. The mother tries to spread towels, but is foiled by the lick and curl of the wind.

“The lilo’s going to blow away,” she says.

“It’ll be fine.” He unfolds the lilo and begins to inflate it. His wife lays herself elegantly out on the towel and bastes herself with oil.

The children’s run ends at a large square pillar of rock, as big as the hotel they left that morning.

“What’s it for?” asks Finn.

“It’s a rock,” his sister tells him, enjoying the opportunity to patronise. “It’s not for anything.”

“There’s people climbing on it.” He points to three precarious figures teetering on a narrow path, yelling encouragement.