I know there’s something in the lobster pot before I start to lift it. Down there on the sea floor, I can sense the creature I have caught. It’s eaten the bait and tried every way to escape, finding its huge claws to be only a hindrance. I do what any good seaworker would do and concentrate on how badly Northaven needs to eat. Food shipments from Brightlinghelm are becoming unreliable and we don’t have good farming land round here. Up on the cliffs there is moorland and marshland, not the green and golden wheat fields that you hear of in the south. Our last harvest was shredded by the gales. This runs through my head as I pull the rope up from the sandy floor, bringing the unlucky creature into my boat.

I love the blue melt of the sea and sky, the salt spray, the way I have to balance on the swell, the sun dazzling, the wind lifting my spirits high into the air. I reckon I’m a natural on the water – like my pa. My brother Piper is a senior cadet, training for the war. So when Pa died, the boat was left to Ma and me. As a widow, Ma is not supposed to work outside the house, so in those dark years after Pa’s death, I taught myself his trade. I think I had it in my bones. Pa knew I liked the water. He’d take me out with him when I was barely old enough to walk. He’d move about the boat, grinning at me, showing me the wonders of the sea. I love the moving waves so much that when I step on solid land, I feel all heavy and bereft.

I look at the lobster: a huge female. I see her egg sacs, held precious under her belly. I admire her blue-black armour, her otherworldly eyes. I’m opening her pot when I realise I’m no longer alone.

I smile with delight and I thrill at the danger. Rye Tern has come.

‘How’s the catch?’ he asks.

I see him then – or sense him, I should say. Songlight can’t be described in words. Rye’s with me, but he’s not. I see him, but I don’t. He’s here in every sense – but only my sixth one perceives him. He’s leaning on a mop, his shirt sleeves rolled up. He’ll be somewhere in the barracks, but to me it seems like he’s standing in the stern. The sun still shines through him but as our minds cleave to one another, he grows more solid. ‘We were parading and I saw your boat. Got myself put on punishment duty so I could come.’ He brandishes his mop. The way he smiles through his troubles makes my heart flip upside down.

‘Reckless idiot.’ I turn to my work, considering the lobster.

Rye comes closer. ‘She looks a bit like you.’

‘I’m better defended.’ I melt at his grin.

His light is closer still. I’ve no defences against Rye at all.

‘She’s carrying her egg sacs,’ I tell him. ‘So she has to go back in the sea.’

I lean over the side and let the lobster queen slip back into the water. We watch her disappear down into the blue. Her freedom makes me glad.

Rye comes out to my boat whenever he can. It’s the only place that we feel safe, where our love isn’t hidden. We can let ourselves go here, high into the air, circling each other like gulls – or we listen to the deep. We can tell when there are herring coming – we sense their sleek glide, all singing the same note. Sometimes there are yellowfins, speeding under us like shooting stars. Always there are jellyfish, drifting in shoals like the souls of the dead.

His songlight is all I’m aware of now, his presence joining with mine. Desire twists in my guts as I remember the last time I touched him for real … As night was falling, a tap came on my bedroom window. Rye was there in our garden, vulnerable, his jacket ripped from a fight with his pa. I cherish that image of him. It comes into my mind, over and over – the way the moonlight fell upon his skin, the hurt that I could sense in him. I climbed out of the window and he caught me in his arms. I held him close, not wanting to speak. The intensity of his body took my breath away. The smell of him, the iron of his arms, his lips on my neck … Nothing in songlight could ever come close.

Together we went down to Bailey’s Strand and swam. We lay on the sand, under the stars. We heedlessly broke every rule and restraint. Thinking of it now – of being joined with his body as well as his mind – makes me crave for it again. I want Rye Tern here, in my boat. I want to smell him, kiss him, explore him with my hands. Rye can tell what I’m thinking of. I feel his longing in every breath.

What we’ve done is interdicted. According to the Anthems of Purity, which we must learn by heart, I am now tarnished. But how can such a thing be criminal? We are not sex traitors, we are Elsa and Rye.

‘I have to see you,’ I whisper.

‘I know,’ he says. ‘Something has to change. We have to be together.’

‘Meet me,’ I tell him. ‘Down on Bailey’s Strand. Tonight. In the flesh.’

‘It’s dangerous.’

‘I know.’

Our songlight is one keen note of desire. I want his lips on mine, his belly pressing against me, my legs wrapped around him. We hold the note, breathing our need, until the whole ocean feels like it’s singing to our tune.

Then I sense him looking over his shoulder. For a second I see the world through his eyes. He’s in the refectory, mopping the floor. I hear heavy footsteps approaching him.

‘Someone’s coming,’ he says. Instantly, his warmth and vigour fades.

He’s gone, leaving me in turmoil.

The quality of the sound all around me changes. I become aware of the breeze, the water lapping against the sides of the boat. I hate it when he vanishes suddenly like this.

I pull in my nets and I turn back towards Northaven. My songlight isn’t wanted there. I keep it buried underneath my lungs. I push my songlight down my legs and arms and hide it under my fingernails. If anyone else in our town has songlight, they must keep it well concealed. To my knowledge, it’s just Rye and me. In Northaven, songlight is a burden; it’s treacherous. Occasionally, I’ll sense a note on the air like the colours of the loom, or a sigh like water falling down a drain, or thought-wreathes hanging like the crackling of a fire. And then the singer notices and suddenly it’s tight and hard to breathe. I know the feeling. When Great Brother Peregrine took power, back when Ma was a girl, there were culls of all unhumans. Our temple to Gala was closed and locked. Anyone known to have songlight was cuffed around the skull with lead and taken to Brightlinghelm to be enslaved. Every few years, an Inquisitor comes with his Siren to inspect the population. Last time, the Inquisitor took old Ellie Brambling, Mr Roberts and Seren Young. I was a junior choirmaiden then, and my songlight had not fully shown itself.

Before the Inquisitor left, he stood with our eldermen and drilled us on how to spot the signs. If we had this mutation, this corruption, it would soon become apparent. If we sensed any signs in ourselves or in others, we were beholden to confess. Did we, when alone, ever feel the presence of another? Did we ever sense what others might be thinking? Did we experience a sensation of floating, of being out of our bodies? Did we ever feel controlled by the will of another? If we suspected an unhuman at work or felt an unhuman stain upon our souls, we had to come forward and speak. If we were honest, no harm would befall us. Our songlight would only be contained. We’d be able to use it in service of the Brethren.

‘No thanks to that,’ I thought, as my songlight developed in full flow. Night after night I’d wake and find myself high above our house. I would be out in the boat and find myself looking down from the sky, feeling birdsong like a language, or seeing the world through the eyes of the seals that watch me as I work. I felt intensely connected to every living thing. And very, very afraid.

Then one day, Rye Tern showed up in my boat. I’d known Rye all my life – he was one of Piper’s friends. He appeared in songlight when I was pulling in my nets. I tried to ignore him, my heart thumping with fear. Unhuman. Unhuman.

‘I know you can see me, Elsa.’

‘Leave me alone, unhuman,’ I told him.

‘You’re unhuman too, fool. What’re you going to do about it?’ he asked. ‘Turn me in?’

I had nothing to say; just a slow tear that fell down my face.

‘It’s like your worst fucking nightmare, isn’t it?’ said Rye quietly.

I nodded.

For a while we prowled around each other like cats, claws out, not daring to trust. But it was such a relief to have a friend. I’d been so lonely with my oddness, so scared when it began. It was far worse than my monthlies. The pain and the blood-cloths were nothing compared to the fear I felt when my mind began to leave my body. When I began to glimpse the underthoughts of...