Any child unfortunate enough to be born in my hometown knows that there are strange creatures in the lake. Parents warn their children about electric eels, sea serpents with two heads, sharks with a taste for the blood of children – anything to keep them out of the water. It’s not like the lake is enticing; there’s no crystal clear cool water offering escape on a hot summer’s day. No, The Wash is a lake straight out of a horror story, a thick grey soup with the smell of a demon’s armpit, or worse. It’s the stuff of nightmares, and the site of many an adolescent dare.

Unsurprisingly, tourists never flocked to Juniperville, with its hideous lake right in the centre of the town. Forty years ago, the town leaders came up with a plan: turn the main shopping area into something straight off a 1950s’ film set. They went overboard with the pastel-hued façades, the neon signs, the wholesome diner and the drive-in, where wait staff roller skate up to car windows to take orders and serve food.

It’s a strange place, my home town. Throughout my last year of high school, I couldn’t wait to leave. My best friend Rufus and I had solid plans to get out; we’d work as many hours and save as much money as we could, so that we could go travelling for a year before going to university. The summer after we finished school, Rufus worked double shifts as a waiter and as a cook in the diner, and I worked twelve-hour days for the parks department, planting and tending to the flower beds around The Wash (which my grandad dismissed as “lipstick on a pig”). It was hot, tiring work but, as my father told me almost daily, I could count my lucky stars that I was working outside and not in a hot, windowless factory, like he did.

When I started high school, he took extra shifts to kick-start a higher education fund for me. He approved of our plans to travel for a year, but said,“Your university fund is not going to be used for traveling. You go away and enjoy yourself, but you pay for it. When you come back, the fund will be here, waiting for you.”

I had every intention of it, too. I couldn’t wait to travel, but I was also determined to knuckle down and become a serious student once I returned. However, after what happened that summer, I left Juniperville, and I haven’t been back, not in five years. As much as I know they love me, I’m pretty sure that my dad and younger sister are relieved I’ve stayed away, because everyone else in the town believed I was responsible for Rufus’s disappearance, and his parents were baying for my blood. They might still be.

A few minutes ago, my sister phoned me. “The Wash is giving up its secrets. The water level is at its lowest since records began, and stuff is floating up to the surface. Last week, it was a car door and the passenger seat. They’re planning to send a dive team down again at the end of August, to look for him.”

Everyone in Juniperville thinks that Rufus drowned in the lake, after we took his canoe out late one night. No one believed me when I said I wasn’t with him. I didn’t tell them that it was a set-up, one to pin the blame on me. No one questioned why Rufus’s new girlfriend – who appeared in the town just as breezily as she left it – wasn’t seen again after that night. It was tantamount to collective amnesia.

“Will you come back, for the search, in case they find him?”

I could hear it in her voice, part plea and part wish I’d let old wounds stay healed. “I’d just upset people if I showed my face.”

“Being there if they recover his body would be a good way to honour him.”

I couldn’t argue with that, but at the same time I couldn't tell her that there was no body to be found. “I’ll think about it,” I told her, meaning it.

“Where are you right now?”

“We’re all at the summer house, on Skye. I’m trying to finish my dissertation, but it’s not going well.”

My sister is five years younger than me, two years older than I was when I left Juniperville. She’s studying to be a doctor, making our father proud.

“I miss you, Lina, and I’d love to come back and see you and Dad. Give me a bit of time to see if I can work it out. I’ll let you know as soon as I can.”

My instinct, ever since leaving, was to stay far, far away from my home town. Work and my own studies kept me so busy that, even if I’d wanted to go back, I had a genuine excuse for staying away.

I watch as the cursor flashes on the screen in front of me, picturing all of those cars rusting away in The Wash. Back when my father was a boy, every winter the town held a “Guess the Sink Date” competition. A car was driven out to the centre of the frozen lake, and townsfolk bought tickets guessing the date and time of the big thaw, leading to the sinking of the car. The nearest guess won a new car.

The Wash is giving up its secrets, Lina had said. For the past five years, I’ve been consumed with trying to find out just what those secrets are.

I’m more than thirty thousand words into my dissertation, already way over the limit for a Master’s degree. I have some serious editing to do, but I have no idea how I’ll decide whose accounts don’t make the final cut. I go back to the video I was about to watch before Lina called, which starts with a close-up of Daniel Sandiman’s leathered, sad face. He’s looking down at a black and white photograph in his hands, which are shaking slightly.

My voice, barely audible, says, “Tell me about Leona.”

Still staring at the photograph, he says, “She lit up my life – it’s as simple as that. Every day I knew her was pure happiness. She never stopped smiling, was the kindest person I ever met. It took her half an hour to walk down the high street, because everyone wanted to stop and talk to her. She had time for them all. She made sure no one wanted for anything – she’d pick up bread and milk and anything, really, people needed, if they couldn’t get out and about themselves, like. She was a bright ray of sunshine in our wee town.”

His voice caught on the last word, and a single tear rolled down his face. “She was the most beautiful girl I’d ever seen – in real life, or in the pictures.”

“What happened to Leona?” my voice asked, just a whisper really. I’d heard the story and it felt almost cruel to ask this sad, lonely man to talk about the worst thing that had ever happened to him.

He took a deep breath, then looked up at me. “They took her from me. Right from under my nose.”

“Can you tell me who took her from you?”

“Those bloody Finfolk,” he said, his voice breaking again. “They came here, and they stole the most precious thing I had. That any of us in the village had. All these years, I’ve had to live with it, knowing she’s down there with them, hating myself for not stopping it.”

“How could you have stopped it?” I asked.

“I should have stabbed him, right through the heart,” he said, hatred in his voice. He stared directly into the camera, his jaw juddering from side to side with emotion.

“Daniel, how would you describe the Finfolk, to those who don’t know?”

As Daniel talked about the water beasts – fins instead of arms, tucked under long cloaks to hide their true shape – I tuned out, picturing instead the creature I’d seen emerging from The Wash that last summer in Juniperville. She didn’t look like something out of a fairy tale. She looked to be wearing a wetsuit, from the tips of her toes to her neck. As she stepped out of the water, I saw that she had a slight hitch in her walk, her right leg dragging, her torso bent at a forty-five-degree angle. The more steps she took, the more fluid her movements became, although the slight drag on her right side remained, all of those weeks I knew her.

That’s how I knew that the girl in the diner was the creature I’d seen coming out of the lake that night. I knew it sounded crazy, but I also knew I was right. If I’d known what was going to happen I, like Daniel, would have done something to stop her. I knew there was something off about her, but I had no idea what she was capable of. I didn’t know that she would make Rufus fall in love with her, then steal him away to live with her in The Wash. I knew all of it before I had the vocabulary – the knowledge acquired through research, through countless conversations with people who’d seen things similar to what I saw – to know that these creatures really exist.

Shape-shifters, Finfolk, merpeople, grindylows – even though I wish it wasn’t true, I know for certain that they exist. And one of them stole my best friend.