Although there were three years between us, people often said that Rosie and I looked a lot alike, with our green eyes and honey-coloured hair, but the similarities ended there. Personality-wise, we couldn’t have been more different. I liked science; Rosie liked spooks. I liked telescopes; Rosie liked tarot cards. I liked shopping with my friends; Rosie liked holding seances with hers. Mum thought it was odd that Rosie was into all that spooky stuff given that she’d been so ill as a young kid, but I reckoned it was probably a big part of why she’d become interested in the first place.

Today my little sister was wearing a black T-shirt with a cartoon ghost printed on it, along with the words: I Believe. And as usual she wore a selection of crystal jewellery – her favourite rose-quartz angel hung on a chain around her neck, and she also had on a lace-agate bracelet. Thanks to Rosie, I knew a lot more about crystals and their meanings than 19I ever really wanted to. Rose quartz represented unconditional love, and the angel pendant had been my gift to her last Christmas. The pale blue lace agate was supposed to encourage self-confidence.

“The first two lighthouse keepers ever to stay there went missing, and no one knows what happened to them!” my sister went on gleefully. “Here, look at this!”

She thrust her phone at me. She’d been going on about a reported sighting of Bigfoot last week, and it had been UFOs spotted flying over Sainsbury’s the week before that. This time it was lighthouses. The lighthouse on Bird Rock in particular. The article read:

Finn Lewis and Niall Abernathy were both experienced keepers of many years. They’d been stationed at the new lighthouse on Bird Rock for only a month in 1807 when the unthinkable happened. Cut off from the outside world, no one had any inkling that anything was wrong until a couple of passing ships reported that the lantern wasn’t operating in bad weather.

The Northern Lighthouse Board attempted to communicate with the men via radio, but their calls went 20unanswered. Finally a relief team was sent to investigate. When they entered the lighthouse, they knew at once that something was terribly wrong. There was no sign of either Finn Lewis or Niall Abernathy. The men had simply vanished, yet their boots were lined up on the shoe rack, and their waterproof coats still hung from pegs.

Not only that but a long-cold supper lay untouched upon the table – a feast for the flies. There was no sign of any disturbance – it was as if the men had simply got up one day and walked out. There was no way they could have left the island without a boat, and yet there was no trace of them.