It is a Sunday night in late October and there are no boats in the bay. Every few seconds, the lighthouse beam sweeps across us. Dad links his arm with Mum’s, while I walk ahead. I’m carrying Dad’s lantern so we can see our way along the path in the dark when the flashing light is facing the other way.

We are the only people who live on this island, and the lighthouse and cottage are the only buildings here. The sea around us is filled with rocks that are as sharp as swords. As sharp as your worst worries.

Those rocks are hidden beneath the waves. They can sinks ships and take your life. They have killed many people in the past, and they will cut you to shreds if you let them. That’s why the lighthouse is here, to warn of those dangers.

But Mum and Dad will be all right in our small boat. Dad is a good sailor and knows how to navigate in the dark. And tonight the sea is calm.

Soon the jetty and the boat are in view. Gentle waves lap against the stony beach and the boat’s hull. Dad steps down into the boat, and I pass him the lantern.

Mum hugs me goodbye. I put my hand on her belly, which is as round as a ball. The baby kicks beneath my palm and Mum winces.

“I will miss you,” I say.

“I won’t be gone long, Deryn,” Mum says. She’s smiling, but her eyes are full of worry.

“Why don’t you let me come along?” I blurt out. “I could look after you.”

This will be my first time alone on the island. I haven’t ever been away from my parents before, and they have never been away from me.

“I’ll be fine,” Mum tells me. She wipes a wisp of hair from my face and kisses my cheek. “We’re going to stay with Grandma, like I did when you were born. Your dad will fetch the midwife, and she and Grandma will both be there to help me during the birth.”

“What about me?” I ask. “What should I do?”

“You’ve got the most important job,” Mum says. “You must stay here and take care of the lighthouse until we get back.”

“When will that be?”

“Tomorrow,” Dad says. “As soon as Mum’s had the baby. You’ll be fine to make your way home in the dark, won’t you, Deryn?”

I nod. “I have the light to guide me,” I tell Dad.

“Good,” he says. He sounds a bit unsure. “Keep the watch, and promise me you’ll do your school work and chores in the morning. I don’t want you spending the day running around the island chasing sea birds!”

“I promise,” I say.