I fold the paper back inside and then tuck the brass locket into my shirt, my fingers briefly tracing the raised butterfly design. I guess it’s fitting that I ended up working at a butterfly zoo, but then I’ve always loved the tiny creatures. The locket is all I have of my mum, so to me butterflies are an emblem of hope, a sign that one day I’ll find her.

And now maybe I have.

I’ve spent years posting on missing person sites asking for information, and last week someone actually replied. The man said he was looking for his brother when he came across my photo – he has a memory for faces and I looked like a woman he’d met on holiday once. She lived at the lighthouse on Bardsey Island, off the west coast of Wales, and he saw her go to the mainland with her baby and then come back alone. He seemed so certain and the dates checked out, and somehow I just have this feeling.

Getting to Bardsey isn’t easy – a bus, two trains and a boat crossing – so I decided to send her a letter with my number. That was seven days ago. From what I’ve read online the island is tiny and barely populated so it’s not going to have the best postal service, but even if she’s moved surely someone would have received it. I fiddle with the silver stud in my nose and sigh. One thing’s for certain, I can’t stay in here. My boss will notice I’m missing and I’m the only assistant in work as Tom is late again, which means I have to give this morning’s talk.

I crawl out from my hiding place then wrap my arms around a display case which is almost as big as me. There are plenty of smaller ones, but I haven’t done three years of martial arts training to take the easy option. With a grunt of exertion, I lift the case and shove the door open with my foot. I love my job – I enjoy seeing the customers’ excited faces when a butterfly lands on them and I like teaching them about the different species we have at the centre. I just need to pretend it’s an ordinary day at work. You know, forget that my entire life could be about to change with a single phone call.

As I enter the glass butterfly house, I’m greeted by the familiar sound of wet hissing from the vents, a constant tic-tic and fizzling hum of artificial jungle. It’s always warm and humid, but the air feels stifling today. Beneath the scent of nectar is a cloying smell of overripe fruit and rotting vegetation and something I can’t quite place: a stench of decay that doesn’t belong here. It sits on my lungs and makes it hard to breathe.

Tightening my grip on the case, I head to the display area on the far side of the room. October half-term is one of our busiest times and the walkways are full of visitors. They wander amongst the glossy-leaved plants and tropical orange flowers, pausing every now and then to point at a flash of colour flitting about their heads. In other words, not looking where they’re going.