So it took him by surprise, one May morning, when he went down to the shop for rolls and fell in love. She was a woman of about his own age, small and plump with the strikingly dark hair and blue-white skin you sometimes get on the west coast. Her eyes were the slate-grey of the sky over the Minch that day. Both of them picked up a paper and they started agreeing violently about the mess that was the Middle East. Dougie had never had a conversation like this before: one that danced from North Africa to the smell of gorse to the right jam to have with the morning rolls. She favoured gooseberry and made her own. If he came by she would let him have a pot. Catrina had just moved into the cottage beyond the harbour. 'I'll be in all afternoon,' she said. 'I'd like your opinion. Not many people really see the sea and I'm not sure if my painting's caught it.'

     'I'll drop in after lunch,' he replied, mentally rearranging his day.

     Dougie had always been a good lad, but now Mr. and Mrs. Macleod were black-affronted. For what respectable woman would be living in an isolated cottage on her own? And she was godless. Under an old seal-skin coat that made her look even fatter than she was, she tramped about in men's garments, jeans, and tight tee-shirts, an abomination unto the Lord. Dougie was round there at all hours, not like their boy at all. Even the minister speaking to him had had no effect. Last night Dougie had come in past eleven and his father had smelled drink on him. The boy hadn't even denied it and had been given an ultimatum. Either he gave up the woman, and the drink or he left the croft. The Macleods had always kept a decent house.

     Now Mrs. Macleod was worried. If Dougie wasn't downstairs soon he'd be late for the kirk. 'Dougie!' she called. 'Come and have a bite before the service. I've made you a fresh pot of tea.'

     'I'm not going,' her son shouted back.

     'Are you not well, son?'

     'I'm fine. I'm just not going,' he replied.

     Her husband put down his cup and strode through to their son's room. 'Right,' she heard him shout. 'I've had enough of your nonsense. Get yourself washed and dressed for the kirk right now.'

     'Or what, dad?' Her son's quiet calm frightened Mrs. MacLeod.

     'Or you can get out. You either behave yourself or get out.'

     'I'm twenty-nine dad,' Dougie murmured. 'I can judge for myself how to behave. If that's not good enough I'll just have to go.'

     There was a long silence. Then, 'I'll give you till we get back to think it through,' said her husband. Their son didn't reply. After the longest service Mrs. Macleod had ever endured, they left the kirk as fast as they decently could. The croft was empty.

     Physically, mentally and, yes, spiritually Dougie felt blessed. He and Catrina had been living together for a year and he wondered how he'd done without happiness for so long. Years ago, practising joined-up writing, he'd copied, 'God is Love,' over and over, mildly puzzled. Now he understood; he was living what that meant. Catrina was happy too. OK, she needed her space, peace to catch the exact gradation of the light that never stood still, the odd solitary walk along the night beach. But he was the only one who could see exactly what she was trying to capture in her grey and mauve and turquoise and teal paintings. They discussed light and sea and sky for hours at a time. Dougie being away for six weeks then back for four suited Catrina, gave her the freedom she needed to get on with her own work, made his homecomings all the better.

     When she fell pregnant, things changed for Dougie. For the first time, he worried about her. So he looked around and found a post to retrain as a maths teacher on the island. When Dougie quit the rigs, Catrina wasn't best pleased. Things had been fine as they were, better in fact. He'd done it though and she preferred liking it to lumping it. Soon she was back to normal. She even started to appreciate his cosseting. Being little and round to start with she swelled quickly and they both laughed when he called her Beach-ball. Mostly she enjoyed company on her long tramps along the shore but sometimes she insisted on a solitary night walk. An hour or two after they'd gone to bed she would get up. 'The tide's changing,' she'd say. 'I always get restless when there's a full moon and the tide's changing.'

     If you love someone you don't hedge them in and Dougie tried, but his anxiety grew as steadily as the child inside Catrina. One night he felt her rise. He kept his eyes closed, his breathing slow, and waited. Then he followed her along the strand, keeping well back, just to make sure she was all right. Moonlight glistened on her old coat and he wondered again that she was so attached to it, for she was fond of the seals that bred here. But she claimed it was the only garment that kept her warm. As Catrina approached the water's edge Dougie noticed half-a-dozen seals' heads, dark on the silvery surface. Catrina kicked off her shoes and walked into the waves. Typical, he thought, but it's a warm enough night. Then he saw her hunker down and slip into the glimmering water. She shouldn't be swimming in her condition.

     Dougie realised she hadn't taken off her coat. It would get waterlogged and drag her down. Sprinting seawards, he yelled, 'Catrina, Catrina come back. The currents there are dangerous.' She turned but a cloud had floated over the moon and he couldn't see her clearly. Several seals were bobbing around her, their heads towards him. The darkness felt threatening. 'Catrina!' he called but she didn't answer. As the cloud drifted away he began to see clearly. A pod of seals gazed placidly at him and he scanned each dark head in turn, fear thickening. Seal after seal met his gaze. Then they turned together and dived, re-appearing twenty yards further off-shore. The line of small rounded footprints leading into the sea had filled with water.

     Dougie couldn't swim but he waded out chest-deep, uselessly. Sharp little waves leapt at his face and he could feel the current sucking warmth from his body and tugging his legs seawards. Under the glare of a lunatic moon, he turned and fought the water's pull back to the shore. He returned home, exhausted and shivering. Catrina's nightdress was under the pillow, her clothes neatly folded on the chair. She must have been naked under that bloody coat. He phoned the coastguards then changed into dry things and walked the sea edge, a mile in each direction, while the rising tide washed away her footprints. Catrina was dead. At sunrise, Dougie returned to the cottage and heard singing. He ran upstairs and she was bathing, her sealskin coat on the bathroom floor. 'Morning love,' she said. 'It was such a lovely night that I walked and walked. Did you go for a walk too?'

     'Yes,' said Dougie. 'I went for a walk. I saw some seals swimming and watched the dawn come up. I thought I saw you swimming too.'

     'I didn't even paddle,' she said. 'Moonlight plays tricks when you're tired.' She gazed placidly at him. In his chest, a diffuse fear congealed to a rubbery lump.

     When the local policeman arrived to say the coast guards had found nothing, Dougie apologised and explained that Catrina had turned up safe and sound. He slept for twelve hours and, feeling better, decided he had hallucinated. A fortnight later Catrina's contractions started. Just before the district nurse arrived, Catrina told Dougie how much she loved him and that, if anything happened, he was to remember that. 'Nothing bad's going to happen,' he said. 'With the amount of herring you eat, the baby'll just pop out.' Dougie was right for the delivery was straightforward and the boy healthy. He had his mother's hair and eyes but a look of Dougie's grandfather. Maybe Dougie's parents would finally come round.

     The first few days were a hectic, happy flash. Catrina stayed in bed, learning to breastfeed while Dougie spent every waking moment changing nappies or shoogling Lewis. Four moons came and went, unmarked by Catrina, unmentioned by Dougie. One evening, when Lewis was five months old, he wouldn't settle. All-day the sky had been sullen and now thick clouds hid the moon. His mother fed Lewis repeatedly and his father walked him up and down but he kept on crying. 'It's colic, sure as eggs,' said Catrina.

     'Maybe we should get the doctor,' said Dougie.

     'Let's try gripe water first. It'll only take half an hour to fetch some.'

     Dougie was whistling as he drove back. Before Lewis had been born, things had been great. Now they were perfect. As soon as he pushed the front door open, the silence struck him. The wee one must have dropped off by himself, the best way. Dougie tiptoed into the bedroom and up to the cot. Lewis was as peaceful as if he had never known a moment's discomfort. Dougie glanced towards his wife. Catrina never slept in an orderly bed but tangled all the covers into a sort of nest and dived under them. He tiptoed over. The bed was empty.

     Dougie ran round the house then onto the dark shore, calling, but Catrina was nowhere. Some swarthy heads broke the sea's angry surface then vanished. On the close-cropped grass bordering the sand, a dark shape stirred but it was only a sheep tottering into the deeper darkness inland. Remembering his sleeping son Dougie hurried to the silent house. Lewis was still sleeping safely and Dougie's heart stopped pounding. He made a cup of tea then took his time searching. As he'd expected, none of her clothes were missing, except her sealskin coat. He waited till well after dawn before calling the coastguards. After three days they called off the search.

     Though reconciled with his parents, Dougie could now barely tolerate their religion. He was convinced he'd lost Catrina through something faint-hearted in himself, something held back, and for that, he blamed the kirk. Dougie watched the sea's edge through many a moonlit night, but his son never knew his mother. Lewis grew into a pale, spindly adolescent who neither flourished nor foundered. Although he and his father were fond of one another, neither had a lot to say. On Sunday afternoons they visited Dougie's parents who tried to feed Lewis up with roast beef and Yorkshire pudding but their grandson was picky, nibbling the trimmings and neglecting the meat.

     Despite living on the sea's edge, Lewis didn't learn to swim till secondary school when there were lessons once a fortnight. He took to swimming like a dry garden to rain. In the staff room, the PE teacher told Dougie that Lewis had real talent. He added, 'Of course, he'll never be a serious swimmer, not with his build.' Dougie smiled grimly; after all, he couldn't stop the lad. From then on, Dougie drove Lewis to the pool most Saturday mornings, for even in summer he wouldn't let the boy swim in the sea. The currents in that bay were far too treacherous.

     At seventeen Lewis got a place at Robert Gordon's, so off he went to Aberdeen to study. His dad helped him carry his stuff into the flat he'd be sharing with two other new starters. Lewis was the only local lad going to Aberdeen that year so he ended up with two foreigners. Dougie wanted to meet them. He wasn't worried about the Malaysian but, after the horror stories from the war, he wanted to check the Japanese lad wasn't a psychopath. Ito seemed nice enough, and Dougie was happier than he'd expected driving home. He wished Catrina could have seen Lewis. He was still a skinny wee thing but a lovely lad. You couldn't ask for a better son.

     It might have been the east coast air or the food or the exercise, but Lewis thrived in Aberdeen. He joined the college swimming club and got a place in the reserves. The three flatmates became friends and took it in turns to cook the evening meal. Maybe it was the densak or maybe it was the sashimi or maybe it was the daily training sessions but Lewis's appetite improved. It certainly wasn't his own contribution to international cuisine for after the first two weeks of sausages, oven chips, and pizza, Lewis dropped his 'Scottish' cooking and started copying Ito. In Aberdeen, it was possible to live frugally on the freshest of fish and they often ate herring three or four times a week. By Easter, Lewis had grown two inches and put on ten kilos. The following summer he started dating Kirsty Greenwood's youngest daughter, Jess.

     Lewis became president of the college swimming club. The first time he went swimming in the bay where he had been born, his apprehensive father stood guard on the shore. Dougie couldn't help but be proud of his son's grace and nonchalance in what were genuinely treacherous waters. 'He's in his element isn't he?' came a dry voice. Dougie hadn't heard the minister approaching and started, suspicious. But the old man's gaze was friendly. He was just out walking his wee dog and making conversation.

     'Aye,' said Dougie. 'He's in his element all right.'

     Lewis's night swims started the summer he was twenty. When Dougie heard his son go out he kept under the covers and prayed for the first time since losing Catrina. Maybe his prayers were answered for his son returned safe and sound. Maybe they weren't for the lad continued his sea-bathing whenever there was a moon, winter as well as summer. Lewis's prowess grew and he competed at national then international level. Of course, he became famous for his Olympic bronze but, although he was fast, stamina was his real gift. When he swam right round the island a reporter from the Press and Journal heard about it. It made the front page and he repeated the feat for Cancer Research. The following summer he made the front page again with a more spectacular exploit. Although only the Press and Journal headlined the 'Boy who swam the Minch', the story went viral online.

     That changed Lewis's life, for the owner of a Tokyo restaurant chain read an article in The Independent, crediting raw fish for his stamina, and invited him to Japan. Lewis's promotional swims between Japanese islands are legendary but more importantly, he met Yuki. His marriage broke Jess's heart for two whole years but pleased his father. Yuki and Lewis had three children, all healthy testaments to the nutritional advantages of sushi and sashimi. Like his mother before him, Lewis valued his privacy and had asked his family never to disturb him bathing. One moonlit night in springtime however he forgot to lock the door of their big Japanese-style bathroom. When she accidentally intruded, Yuki backed out immediately, scarcely glimpsing the glistening black hump in the dark water. Yuki loved and honoured her husband who loved and honoured her. She buried that image forever, for eye and mind and moonlight play many tricks. They were happy all their days.

     Dougie visited his son and daughter-in-law in Hokkaido yearly and his later years were gladdened by their happiness. For his son's sake as well as hers he was grateful that Yuki had proven stronger than he had managed himself. Back home he continued to walk the shore in the moonlight, whether eerie or benign. Sometimes there were seals. Once, when his granddaughter first swam for Japan, he shouted his news across the waves but none of the bobbing heads turned. Dougie's blood still quickened at any noise from the pools of shadow around the rocks but no ageing woman in a damp coat ever appeared. Still, he hoped. It could happen.