You’re not supposed to let them in. They appear every rainy night and mope around the alleys. All city folk know they’re coming and dim the lamps in case they come knocking. We eat and drink by candlelight and lower our voices when a shape ambles by the window. Some look more human and some are more misshapen with distorted or horrifying features. They never come knocking. It’s like they’re on their own plane and walk all night, only to evaporate when the pale morning light glints off the dirty, metal city.

“Busy night tonight,” Ms Jade remarks, cleaning the bar with a rag. She jerks her head towards the rain-streaked window as a couple of shapes slide by. “Mind he gets you home safe,” she tells my daughter sternly.

Saph smiles happily as she swings her little legs off the bar stool. “They’re like sleepwalkers.”

Ms Jade raises her eyebrows at me. “That’s true enough, I suppose. But mind you leave them like that. Don’t go poking the bear.”

“Don’t go rocking the boat,” Saph sang. She must have heard this at her school.

They don’t get taught the rumoured origin of the Rain Walkers until they are older. They say there was a catastrophic explosion of one of the airships transporting citizens from the mainland. That the bodies that fell from the ship were claimed by the Grey Sea. That’s what the Rain Walkers are: the lost souls from that ship exploring the city they never got to touch. The sea spray becomes rain and the spirits fall to land.

“Come on, Saph,” I say, ruffling her hair. “The rain’s stopping. Have you still got your ticket for the metro?” She proudly shows me the ticket. “Good. See you later, Ms Jade. Say thank you, Sapphy.”

“Thank you!” Saph waves and slides off the stool.

“Bye John, bye Sapphire.” Ms Jade smiles.

We leave out of the front door and walk along the road. The cobbles are shiny from the light rain. The metro zoomes overhead, cracking and clunking. If you squint your eyes, the city becomes a blur of neon colours. Huge buildings tower above us, lit up by office and apartment lights. The stars are invisible with the light pollution.

There are a few lingering Rain Walkers up ahead. Some have umbrellas. It is common practice to give them a wide berth, but even if they are approached they won’t acknowledge the living. There is a fine if you touch or attempt to provoke them, though. Just in case.

The metro doors slide shut and it speeds into the night with us inside. It is a spectacular view if you’re careful not to get used to it. This city is a tangle of buildings and bridges and tracks and wires and stairs. People have even created their own ladders to connect homes to family’s or neighbours’. We’re stacked on top of each other here. But it’s a feast for the eyes and it is better to live here than the mainland.

The metro slows at the next platform and the doors open. Sapphire tugs at my sleeve and I tear my eyes away from the building that is the hospital.

“Dad! Daddy! It’s got into our carriage!”

“Who, darling?” I turn in my seat and my eyes meet a pair of milky blind ones as a Rain Walker stands in the carriage, its blurry hand holding on to the pole. Its head is grey and swollen with a mouth too wide for its face. It is grotesque. I have never seen one in the harsh light of the metro before.

“We’ll get off at the next stop,” I tell Sapphire, my mouth a little dry.

“Why? He’s travelling in his sleep!” Saph grins as she peeks at the Rain Walker. “You told me not to be scared and not wake Mum up and just let her do her thing.”

“Oh, Saph, that’s different. Mum’s your mum.”

“Are we going to make sure he’s all right?” Saph asks me.

“I’m sure he’s all right,” I laugh. But it fades out on its own as the metro slows again and the Rain Walker steps out on to the dark platform. For some reason, Juliet pops into my mind. How she had me with her by her bedside before falling asleep for the final time.

It is a quick decision. I grab Sapphire’s hand and we slip out of the doors. Our breath hangs in the cold air. The Rain Walker vanishes down the steps.

“I suppose we could give him some company,” I tell Saph and her face breaks into a smile.

And so we follow the Rain Walker through the maze that is the city. Saph chatters excitedly as we pursue it, speculating where they go to rest or wake up when the rain stops.

The buildings thin and I realise this is the route to Opal Edge. It is an unpopulated plot of land outside of the city. Rumour has it this was the area meant for the rich, the first ever arrivals to the island. Those in charge would have abandoned the operation because of the unstable land. Or perhaps they gave up on this plan after the airship crash, and decided to set up somewhere else to avoid the dark stain the many deaths left on the map. They wouldn’t have wanted a haunting, but here it was anyway.

It’s a large area with views of the ocean. Juliet and I would explore here when we were young. It’s just grass and vegetation. The odd brick and stone. Sapphire and I stop just before the city boundary. We see blue glimmers up ahead as the creature joins several other figures in an area of heather.

We creep closer, treading on the sparse grass, which is alien to us in the city full of fumes. I stop us at a safe distance behind a pair of wizened trees. We watch through the sprinkling rain. The blue lights hovering around the Rain Walkers are butterflies. Genetically engineered. Someone thought it was a sweet idea to blend nature with practicality, as blue light is supposed to reduce crime in the streets.

They seem to be attracted to the Rain Walkers and they dance around their heads. The figures and their umbrellas are slumped together. Sapphire and I watch from through the branches and she squeezes my hand tightly and whispers “Dad!” as we realise they are sheltering each other from the rain and the cold and the night.

We watch for a while. I’m not sure how long. Then I pick Sapphire up, place her on my shoulders, and we make our way home.

“It’s important, what we’ve seen, Sapphy,” I tell her. She mumbles sleepily, and I say, “We should help make things better.”

Sometimes, on a rainy night, I’ll leave the door open and our fire going. The Rain Walkers rarely enter, but when they do, and they wander about a while before leaving, I like to think they have a place of comfort. Maybe one night rain will fall on this city and the living and the dead will both rest peacefully.