‘Dinna fret. Young Murray canna drown - he’s a selkie.’

Sarah wasn’t greatly reassured by Mrs Flett’s words or by the touch of her mittened hand on her arm. Her son Murray was splashing about excitedly in the rockpools, only feet away from the surf rolling onto the skerries, from where the curious seal pups were studying his antics. From their vantage point on the low cliff he looked so slight and vulnerable.

‘But he’s only six, Mrs Flett, and he has no sense of danger.’

Sarah was beginning to regret her candour following her and Murray’s arrival the previous evening, exhausted by the long flight to Kirkwall and the queasy boat trip out to the island. Once Murray had been safely tucked up to dream of the next fortnight’s adventures, a few reviving glasses of single malt from Mrs Flett’s husband Angus and the smoky heat of the open peat fire in the bothy had freed Sarah’s tongue. It had been a long time since she was so open with strangers.

‘Aye, I knew it the moment ye told me the bairn was born with a caul over his head,’ Mrs Flett continued. Her huge, brown eyes seemed to overflow with compassion as she studied Sarah’s worried face. ‘Even today, there’s Orkney fishermen will gi’ a muckle for the guid luck a newborn caul brings.’

Sarah dimly recalled Mrs Flett’s eager account - amidst an alcoholic haze - of the legend of the selkies, seal folk who could briefly assume human form on land but must return in time to their native element. Angus, discovering Sarah was a musician, had even brought out a battered old squeezebox and sat by the fireplace rehearsing an impressive repertoire of selkie ballads while the keen Atlantic winds rattled the bothy windows. Sarah had slipped gratefully into sleep and woken in the morning next to the embers, cocooned with Mrs Flett’s kindness and thick woollen blankets.

‘Well, I hope it brings him better luck than his father brought me,’ Sarah sighed, craning her neck as Murray hurtled into another rockpool.

‘Ye said ye met in Kirkwall?’

‘Yes. At the St Magnus festival. I was performing at a fringe event and he was in the audience. Every time I looked up all I saw was these enormous, brown eyes. Hypnotic and so full of … yearning. Afterwards, we got talking and … one thing led to another. Over the next five days we became inseparable.’

‘And?’

Sarah gulped. She wasn’t used to such direct questioning. She drew her shawl tighter round her shoulders, twisting the fringe between her fingers.

‘The night before I was due to fly back, just when I thought I had found the relationship of my life, he simply disappeared. No note; no phone call. Nothing.’

‘Did ye ever hear from him again?

‘No.’

Mrs Flett shook her head and tutted softly.

‘Ye must have felt so sair.’

‘I was devastated; but once I realised I was just a passing amusement, I was so angry I could hardly think. Then I discovered I was pregnant.’

Their gaze turned instinctively to Murray, who was teasing a crab with a frond of seaweed.

‘Och, that must have been hard. With ye a single woman an' all.’

Mrs Flett’s expression was so kindly it made Sarah want to scream. If only she knew just how hard it had really been, she’d be shocked right out of her cosy benevolence. Hard, indeed, didn’t even come close. She recalled the weeks of misery, agonising over whether to have a termination. Even today, if she were honest with herself, she sometimes questioned if she had made the right decision. No matter how much she loved her son, she couldn’t escape the feeling at times that she punished Murray for the sins of his father.

‘Even though I’ve had seven years to heal, sometimes when I look at Murray I see his father’s eyes.’ Her finger ends, twisted tight in the fringe of her shawl, had gone white. ‘Can you believe, Mrs Flett, that love and hate could be so strongly intermingled?’

Sarah drew her knees up under her chin and hugged them to stop herself shivering. A cold wind seemed to have come from nowhere.

‘Please, call me Murron,’ Mrs Flett patted Sarah gently on the arm again with her mittened hand. ‘And remember, ye’ve no come back to greet over old times. There’s nae peace in that.’

The tears were starting to prickle as Mrs Flett - Murron - stood up and helped her to her feet. Murray was rushing up the path from the shore to display his latest find.

‘Dinna fuss. It’s nae matter,’ Murron insisted. ‘I’ll ask Angus to take Murray out fishing tomorrow. D’ye reckon he’d like that?’

Murray’s keen ears had picked up the suggestion already, and Sarah soon realised that objections would be useless. Besides, apart from a ruined mediaeval chapel and a few standing stones, there was little else to see on the island. Which, after all, was why she had chosen to holiday there, to the astonishment of most of her friends. Why they thought you needed bright lights and false bonhomie to have a good time, she couldn’t imagine. As they walked from the cliffs along the stony path back to their bothy, Murray slipped his clammy hands into theirs, skipping to keep up. He was in that ‘everything in the world is perfect’ mood that always made her want to slap him.

Next day, Angus and Murron were waiting on the beach below the bothy as the sun rose. Sarah opened the door, inhaling the sharp, refreshing tang of kelp and damp heather on the cold morning air, but Murray just pushed past her excitedly. His eyes lit up when he saw the traditional Orkney yole drawn up on the shore, its lines reminiscent of a Viking longboat and tan sails a’flutter in the early morning breeze. Murron helped him roll up his trouser legs to clamber into the boat and leaned on the prow to ease her off the shingle.

‘I’ve packed lunch for ye and Angus,’ she said as she ruffled the youngster’s hair. ‘Be sure tae bring us back a guid, fat lobster, all reet?’

Sarah watched anxiously as Angus hauled in the sails, which crackled into life as the wind filled them. Soon, the yole was little more than a speck against the smudge of the distant mainland and Murray’s hand had long since tired of waving. She listened for a few minutes more to the wild music of the fulmars and guillemots, also heading out for a day’s fishing, before heading back to the bothy. Murron was considerate enough to understand her need for space, so she spent the day working on the new and very challenging guitar composition she was due to perform at the Wigmore Hall on their return to London. She had never felt the need to eat when wrestling with challenges, so the hours passed without even a hint of hunger pangs.

It was only when the light began to fade that she checked her watch. She was alarmed to discover that it was already past nine o’clock in the evening. With the long summer days in Orkney, it was easy to lose track of time. She replaced the guitar in its case and hurried down to the headland where the lighthouse stood. It was the best vantage point, from where, on a good day, one could scan the whole sea horizon from the Pentland Firth to North Ronaldsay. She stationed herself on the cliff overlooking the skerries, where the seals, already ashore for the night, were bleating softly. But by the time the sun started to sink behind the West Mainland, not even a speck of sail had appeared on the horizon.

Murron was standing in the doorway of the Fletts’ cottage, which nestled in a hollow behind the lighthouse, when Sarah finally abandoned her lookout on the cliff edge.

‘Isn’t it rather late,’ Sarah panted, ‘for them to be getting back?’

‘Angus kens the waters,’ shrugged Murron. ‘Fished them all his life.’

She invited Sarah in and brewed her a reassuring cup of tea. They sat either side of an ancient, cylindrical wood stove, on top of which a kettle, blackened with age, steamed constantly. The cottage reeked of ancient lobster creels, damp wool and driftwood. In other circumstances, the cocktail of odours might have been nostalgic, or even comforting. Tonight, Sarah found them oppressive. She sipped at the tea, but her throat was too tight to swallow. After a while, Murron realised that conversation wasn’t helping, so they sat in silence in the gathering darkness.

When the lighthouse started up, the unexpected sweep of light through the window made Sarah start. For a second, she had the ridiculous idea that a police car had drawn up outside the cottage, blue light flashing. The pulse of light swept through the room, illuminating their faces in turn. Sarah could see that Murron, earlier unconcerned, was now equally troubled. Murron lit an oil lamp and placed it on a low table between them, but its soft glow did little to dilute the gloom in the cottage. Though she tried to sound comforting, there was a clear undertone of anxiety in her voice.

‘I’ll just do a wee check on the VHF next door.’

She left Sarah in the pool of lamplight and the sound of her heels on the flagstones echoed down the corridor. After a few moments, Sarah heard the crackle of static, followed by the muffled sound of Murron’s voice. The only words of the reply she could make out were ‘Kirkwall Coastguard’; the rest was in such a strong accent as to be unintelligible. But the look on Murron’s face when she returned told all.

‘They found a yole capsized off Shapinsay. They think it may have been the wash from a tanker.’

Sarah leapt from her seat, nearly knocking over the oil lamp. The mug she had been cradling for over an hour slopped most of its contents onto the flagstones.

‘And what about Murray?’

‘Nae word of Murray - or Angus.’ Murron sat down heavily and looked up at her, the misery in her face evident even in the dim lamplight. ‘But at least your bairn will be safe.’

Sarah stared at her in amazement, which quickly turned to anger as she realised what Murron meant. The flame of the lamp trembled as she slammed her mug down on the low table.

‘Don’t you dare offer me your stupid bloody superstitions! That won’t bring Murray safely back to me.’

She immediately regretted her outburst as Murron unleashed those sorrowful brown eyes on her. But, in spite of herself, the other’s doleful expression, credulous nature and little mannerisms - even the way she always wore mittens, indoors as well as out - were beginning to grate on Sarah’s frayed nerves.

‘Maybe so. But I dinna have even that comfort wi‘ my Angus.’

Murron mopped up the spilt tea and they sat in silence again, the strobe of the lighthouse revealing their faces alternately like some grotesque theatre of pain. The smell of the lamp oil, mingling with the other stenches of bothy life, made Sarah increasingly queasy as the hours passed. Murron simply stared at the flickering wick of the lamp, the light dancing in her pupils, as if the flame held some secret that devout attention would reveal.

The darkness was just starting to thin when the radio crackled into life again. Murron leapt to answer the call. When she returned, Sarah was already on her feet, scarcely able to breathe. Murron took her gently by the shoulders.

‘Guid news. They found the bairn washed ashore on Stronsay. He’s alive.’

Sarah could hold back the tears no longer. But Murron’s grip tightened as she began to slump in relief.

‘Thair’s more. They say a seal carried him ashore. An adult male. A couple on Stronsay watched it in the moonlight. I told ye he was a selkie.’

Sarah realised her fears for her son had made her selfish.

‘So, if that’s true, then your Angus may be safe as well?’

Sarah saw the pain brimming in Murron’s eyes as she shook her head.

‘But Murron, how can you be so sure?’

Murron released her grip on Sarah’s shoulders and tugged at her mittens. Sarah watched in fascination as she slowly drew the rough wool over her short, stubby fingers. For a few seconds they were both in darkness, until the beam of the lighthouse swung again onto Murron’s outstretched hands. Sarah gasped. Murron had spread her fingers. Between them, briefly spotlit in the beam, stretched an extraordinary web of translucent membranes.

Sarah looked into Murron’s eyes, huge, brown and now filled with tears. As she gazed into them, a dam burst deep inside her and a seven year old memory flooded irresistibly back.

The agony was over. Now, at last, she understood.