Leo ordered a taxi to drive him from his splendid Glasgow apartment to the railway station and spent the minutes it took to arrive checking – for the seventh time – that the ashes in the grate were dead, gases were turned off and electricity plugs were disconnected.

The driver was an odious, high-pitched little character, who quickly broached the subject of immigration and spat a racist word into the conversation. Leo requested that he refrain from such language, then, before the man had a chance to respond, pretended to busy himself with his mobile phone, during which he made great play of jotting down the cabbie's name and number in his notebook. Upon arrival at Queen Street station Leo paid him exactly – no tip – and took inordinate pleasure in counting out a stack of grubby coppers as part of the fare.

He purchased his ticket and stowed himself and his considerable quantity of monogrammed luggage in the foremost carriage of the Oban train, which was empty of other passengers. He rubbed his gnarled hands together as he settled down at a seat with a table, and produced a felt-lined box containing a little gold-rimmed glass with harp and shamrock motifs etched on it, and a silver flask with beautiful Celtic knotwork relief. He polished the glass with a napkin, filled it with a shot of Scotch from the flask, took a swig, and settled himself down for a snooze. After adjusting his velvet-lined slumber mask, he fell instantly into an uncomfortable sleep.

A slight jolt of the train is an explosion of light within Leo's dimmed consciousness, followed by a split-second rush of the shockwave tearing the air as it rushes towards him.

He jerked, both in his mind and in the physical world, to avoid the impact, and snapped out of the uncharacteristically brief vision. He found himself blinded by the blast. Panicked, he reached for his eyes and felt the slippery texture of his mask. He tore it off to reveal yet another level of altered reality: massive patches of blond sand deposited upon the embankments of the West Highland Line. He blinked several times, unable to compute this weird phenomenon. Was he still dreaming? Was he locked within an endless nightmare of hallucinations? Then he realised – it was snow. Of course – the Scottish Highlands in winter. Snow.

Leo then endured a brief crisis of hypochondria brought on by the fact that his left leg had gone to sleep during his fitful nap. Having convinced himself that he was about to suffer a fatal stroke, he popped a Mogadon, mumbled a prayer, and urgently proceeded to jot down the hymnal for his funeral Mass, regretting having put the task off thus far. The onus was unsurprisingly on the side of gravitas – Mozart and Fauré – but the sentimentalist in him couldn't resist 'Hail, Queen of Heav'n, The Ocean Star' and then 'Be Still, My Soul' for the exeunt to the hearse. That'll have them weeping in the aisles, he mused morbidly, before realising that the feeling had by now returned to his lower limb and that the magic bullet had calmed his anxiety with its soporific charm. Despite that, he wondered with trepidation what the turnout would actually be at his funeral; he had fallen out with so many friends and associates over the years. He tried to number those who loved him, and pictured one of those melancholy, pitifully attended affairs: a rainy November day, a few old acquaintances shaking hands in the porch of a cold church and murmuring uneasy platitudes for the deceased, politely promising to meet up for a drink one of these days, a white lie at the ready to excuse themselves from attending the wake. Too much gravy and not enough meat in the steak pie.

Leo popped a consolatory segment of Fry's Orange Cream into his mouth, put his earphones in and switched on the radio, but the mountains blotted out the signal. Suddenly, he regretted his parsimony in not having invested in an iPod. 'Join the twenty-first century,' he could hear his friend Stephanie Mitchell, a procurator fiscal, tease. His phone vibrated on the table with a text alert. Coincidentally, it was from Stephanie: 'I told DI Lang 2 xpect u at Loch Dhonn.'

Bloody decent of her.

His thoughts turned to the murdered girl. The picture the police had released to the media was one of a pretty, petite brunette wearing a graduation gown, proudly clutching her nursing certificate, smiling out at the world, full of anticipation and hope. He read the newspaper story for the tenth time:

Police have named the Loch Dhonn village murder victim as 22-year-old Helen Addison. The body of Miss Addison, a recently qualified district nurse, was found early on Thursday morning by a local man. She had several knife wounds. It is not yet clear whether Miss Addison had been sexually assaulted. Police said they are questioning Miss Addison's boyfriend Craig Hutton, 21, at an unnamed Glasgow station and that Mr Hutton was 'voluntarily helping them with their inquiries'.

Speaking for the Addison family, Mrs Grace Dunn, the victim's aunt, said: 'Helen was a lovely young woman, a beloved and valued daughter, sister, cousin, niece and friend, who had returned to her home community of Loch Dhonn as a newly qualified nurse. Her career choice was testament to her caring, compassionate nature. Words cannot begin to describe the devastation Helen's mum Lorna, dad Stuart and brother Callum are experiencing at this time. Her wider family, numerous friends and everyone whose lives Helen touched have been profoundly shocked by this wicked act.

'Someone, somewhere must know who did this. Perhaps they suspect a loved one. No matter how hard it seems I urge you to go to the police. Whoever is responsible may do it again unless you act. Please, you have the power to stop another family going through this hell.'

Leo thought about how the remains of poor Helen Addison would soon be ensconced within an obscure little patch of Scottish clay. And how brutally the months and years would rush by for the people who had loved her, denied her presence at their triumphs and festivities as she was now denied her own triumphs and festivities. The pang of guilt endured at each mundane task, as though performing it in her absence was in some small way a betrayal, an act of forgetting her. And as they speculated forevermore upon what she would have been, the lettering on the gravestone would quickly fade with lichen and the weather, and the rest of the world would march on, blind to the void of her absence.

He recalled his conversation with Stephanie, which had ended in discord when she had visited him three days ago.

'I might as well tell you: I'm going up there.'

'Where?'

He had gestured towards the day's newspaper, which lay front page up on the chaise longue.

'Why?'

'I had a vision. If I get to the scene of the crime I might be able to work out who the bastard is. Being there might stimulate my senses.'

'When are you going?'

'I've yet to decide. I fear if I arrive upon the locus too soon after the event the police may spurn my advances.'

'You likely won't be made welcome, regardless of how long you delay it.'

He had gazed out of the window, watching the rain...