There is the face on the picture postcards, sunny, bright and shining, prosperous and smiling at the world like a toothpaste ad.

But on the other side of the looking glass lies the other face: the real world where all too often the wind blows cold, the rain lashes down and the poverty shows on the outside. That cold hard face was showing as Bob Skinner made his way to work.

The wind whistled down from the North, driving the rain across Fife, with the threat of snow not far behind. It was 6.43 a.m. on one of those fag-end of the year November days when it seemed impossible to relate the dull, grey city to the cosmopolitan capital of the August Festival weeks, or the friendly town invaded on bright, sparkling Saturdays in January by hordes of visiting rugby followers.

Detective Chief Superintendent Robert Skinner brought his Granada to a halt at the High Street entrance to Advocates’ Close. The tiny gateway, unnoticed every day by hundreds of passers-by, led into one of the many alleyways which flow from the ancient Royal Mile, down to Cockburn Street, to the Mound, and to Cowgate.

Skinner stood framed in the entry, the disapproving bulk of St Giles Cathedral, the High Kirk of Edinburgh, looming behind him. He looked as grey as the city itself. Steely hair which sometimes sparkled in the sun now flopped lustreless over his forehead. The last of the summer tan was long gone, and the face bore the lines of one wakened too often from too little sleep.

He was dressed for the occasion, in a long leather coat, black and Satanic, over a grey suit. Only the shoes, light leather moccasins, were incongruous. But even in the ungodly gloom, there was no masking the presence of the man. Standing two inches over six feet tall, he filled the gateway as he surveyed the carnage in the Close. Skinner was forty-three years old, but he retained the grace of an athlete. Power was written in every movement, and in the set of his face, where deep blue eyes, a classically straight nose and a strong chin seemed to vie with each other to be the dominant feature.

He stepped over the tape which had been stretched across the entry way. A group of men, some in uniform, stood around a huddled heap of something, lying where the Close emerged from the shelter of the building above into the open air. Daylight was only a vague promise in the eastern sky as he stepped forward into the poorly-lit alley, hunching his shoulders against the rain and screwing his eyes against the wind.

One of the kneeling men, his back to Skinner, looked over his shoulder, as if sensing his presence, and jumped to his feet.

‘Morning, boss!’ Detective Inspector Andy Martin used the form of address beloved of policemen and professional footballers. He was shorter than Skinner, but broader in build. He was fresh-faced, and looked younger than his thirty-four years. His hair, cut close, was unusually blond for a Scot, and his eyes were a bright green, accentuated by a tint in his soft contact lenses. He was dressed in black Levis and a brown leather bomber jacket.

Skinner nodded to his personal assistant. ‘Morning, Andy. Just how suspicious is this suspicious death, then?’ The whole force knew that the Head of CID did not like to be called in on obvious suicides by nervous divisional commanders.

Martin stood between him and the heap. ‘You’d better prepare yourself for this one, boss. This boy’s been chopped to pieces, literally. I never want to see anything like it again.’

Even in the dim light which crept in from the High Street, Skinner could see that Martin’s face was paler than usual.

His expression grew grim. ‘Just fucking magic,’ he muttered, and stepped forward, past the younger man, towards the lamp-lit heap, which not long before had been a human being.

The first thing that he saw clearly was the face, which seemed to stare at the truncated body with unbelieving eyes. The man had been decapitated. Even as he saw the two pools of vomit on the slope below the corpse, his own stomach churned. In all his years on the force, this was as bad as anything he had seen.

But to his people he was the Boss, and the Boss could not show any trace of weakness. So, switching off the horror, he turned his eyes back towards the scene. The head lay about four feet away from the rest of the body. It had landed, or had been placed upright. Skinner noted that it had been severed neatly, as if by a single blow. He looked again at the face and shuddered. The man, apart from the dull, dead eyes, bore a fair resemblance to Andy Martin.

‘Is everything in the position it was when it was found?’

‘Of course, boss.’ Martin sounded almost offended. Then his tone changed, to an awed murmur. ‘It’s as if the bastard left the head like that on purpose.’

‘Who found him?’

‘Two polis from down the road. One of them, PC Reilly, he’s in the Royal, in shock. The other, WPC Ross, she’s over there. Tough wee thing, eh!’

‘Maybe too tough,’ said Skinner, almost to himself.

He forced himself to turn away from the staring eyes, and from the stream of blood which wound down the close into the darkness, to look at the rest of the body. The belly had been slashed open; the intestines were wound around the fingers of the bloody left hand, as if the victim had been trying to hold them in. The right hand had been severed and lay beside the body. It had been cut off, like the head, by a single stroke, the wound running diagonally from a point two inches above the wrist to the base of the thumb.

Because of the blood, and because of his soiling himself in death or in fright, it was difficult to say with certainty what the man had been wearing. Skinner forced himself to look closely and identified black flannel trousers, once supported by a black leather belt, which had been severed by the disembowelling stroke. The shirt was of a heavyweight woollen check cloth, and had been worn over a thick undervest.

‘No jacket or coat found?’ he asked, then failed to see Martin’s shake of his head as he spotted the briefcase under the body. ‘Did the photographer get all this?’ He directed the question over his shoulder.

‘Yes, sir!’ barked a thin man, anorak-clad and carrying a camera.

Gently, taking care to spill no more innards into the close, Skinner drew the case out from beneath the corpse.

It was hand-stitched, in brown leather. The initials ‘MM’ were embossed on the lid in what looked like gold leaf. There were combination locks on either side of the handle. Skinner tried them. They stayed firmly closed.

‘Bugger!’ he swore softly.

He leaned over the body again. The check shirt had two button-down chest pockets. He undid the flap on the left side, and withdrew a small black calf-skin wallet.

A wad of notes was wound around a central clip. Four plastic cards, two of them Gold, were held in slots to the left, and to the right, under a plastic cover, was an identity card.

‘Christ, that opens a thousand avenues of possibility,’ said Skinner, showing the card to Martin. ‘If this guy was a criminal advocate, and from memory, I think he was, we’ll have to check on every dissatisfied customer he’s ever had, and their relations. If anyone did that for revenge, he must have had a hell of a grudge.’

‘Too right!’ said Martin.

Skinner’s eyes swung toward him. ‘Is the doctor here?’

A slim figure heard the question and detached herself from a group further down the alley.

Skinner watched her approach. ‘Surely to Christ,’ he said heatedly to Martin, ‘they could have sent one of the old lags to a thing like this!’

The woman heard him. ‘Hold on just one minute, Skinner. I am a medical practitioner with scene of crime experience. Since not even you would doubt my qualifications, you must be saying that this is no job for a woman. That is sexist!’

But Dr Sarah Grace’s soft smile was at odds with her combative speech. As she came to stand beside Skinner and Martin, she said, ‘I just happen to be on call this month. There are no favours in this job. But just to restore your belief in the weakness of women, one of those little pools of sick down there is my breakfast!’

The duty police surgeon was young for the job, at twenty-nine. She was around five feet six inches tall, with auburn hair and dark hazel eyes, in which, Skinner thought as he looked at her, a man could easily drown. She was American. Normally she dressed with all the sophistication of a New Yorker, but in Advocates’ Close, in the chill November drizzle, she wore denims and a wraparound parka.

Skinner returned her smile. ‘Sorry, Doc, I stand chastised. Now, can you give me an estimate on time?’

‘He’s still fairly fresh. He was found at 5.30, and I’d guess from the indicators that he’d been dead around ninety minutes by then. It’s a wonder that no one found him earlier. I mean he’s just yards from the sidewalk.’

Skinner shuddered slightly. ‘Just as well. One of my lads is in shock. Imagine some poor wee cleaner on her way to work tripping over a bit of Mr Mortimer!’

He led her away from the body. ‘Can I have a formal report as soon as you can manage, please, Doctor?’ Skinner smiled again at Sarah Grace. The creases around his eyes turned to laugh-lines, and for an instant the steely hair seemed to sparkle.

She returned his request with a grin and a drawl. ‘Double quick, Skinner.’ She stripped off her latex gloves, stuffed them into a disposal bag and thrust that deep into a pocket of her parka.

Skinner looked back towards the mouth of the Close. At the entrance, one or two early morning passers-by had stopped to stare. ‘Andy,’ he called across to Martin, ‘get a screen up there, will you, and move those gawpers on. And let’s have a cover over the body. It’ll be light soon; some clever bastard with a camera would get a fortune for that picture!’

Two constables, without a direct order, stripped off their long overcoats and spread them over the separate parts of Mr Mortimer, pulling the garments together so that they formed a single cover. Two more, the tallest of the officers at the scene, stood shoulder to shoulder at the mouth of the Close. The two who were stationed at the foot of the alley-way moved round the corner and took up position at the head of the steps which led down to Cockburn Street.

‘Right, that’s better. Now you technicians get finished and let’s gather up this poor mother’s son for the mortuary.’ He turned back to Martin. ‘Andy. No weapon at the scene?’ Again, Martin shook his blond head. ‘No, I thought not. Ask Doctor Sarah for an opinion. Whatever it was, it was bloody sharp and handled by someone strong, and an expert at that. A mug would have put a foot in all that blood, but this boy - there’s not a sign he was ever here apart from that thing over there.’

As Skinner nodded over his shoulder towards the body, his eye caught a dark figure running up the alley towards him. He was waving something, something which shone, even in the poor artificial light.

‘Sir, sir, excuse me, sir.’ It was one of the two constables from the foot of the close. His voice was of the Islands, light and lilting, contrasting with the harder Central Scotland tones of Skinner and Martin.

The boy, for he was no more, rushed up to them. He brandished something which looked like a short sword.

‘This was stuck in a door at the foot of the Close, sir. It’s one of those big bayonets from the First World War. I know because my great-grand-father brought one back with him. It’s a sort of a family treasure now.’

Skinner looked at the constable, who stood panting, like a dog awaiting a reward for the return of a stick. Martin shook his head and sighed, waiting for the thunder which he knew was about to crash around the young man.

But the Chief Superintendent spoke quietly. ‘Son, how long have you been on the force?’

‘Nine months, sir!’ The face was still expectant.

‘Nine months, eh. And in all that time, has no one told you that if you’re at a murder scene, and you find something that might be - however slight the chance - a weapon, that you leave that thing exactly where it is and summon a senior officer? Has no one told you that?

‘Don’t you even watch bloody Taggart?’

The young man’s face fell. He looked down at his big feet. ‘Och, sir, I’m very sorry.’

Skinner smiled for the third time that morning. ‘Okay, son. Let’s just say that this is your first really dirty murder enquiry, and you got excited. You’ve just learned lesson one: Keep the head.’ Christ, thought Skinner, as the words left his mouth; what a thing to say. For a second, laughter, as it sometimes can in terrible moments, almost burst out. But he checked himself in time.

‘That’s lesson one. Here’s lesson two. If you ever again come rushing up to me waving a bloody great bayonet, I will take it off you and stick it right up your bottom-hole, sharp end first. Is that understood also?’

‘Yes, sir!’

‘Right, now that it is, show Mr Martin and me exactly where you found the thing. What’s your name, by the way?’

‘PC lain Mac Vicar, sir.’

PC lain led them round the corner and across to a small doorway. ‘It was sticking in here, sir, as if someone had thrown it away.’

‘Try to put it back.’

Like a uniformed King Arthur, the young man slid the brutal knife back into a deep groove in the dirty, weathered doorframe. It stayed in place.

‘Okay, lain,’ said Skinner, ‘that’s fine. Now guard it with your life until the photographer has taken his picture and until the technicians come to take it away.’

As they walked back up the steep slope, Martin spoke. It was the first time since the arrival of his Chief that he had offered an opinion. The care which he took in weighing up a situation was a trait that Skinner admired in his young assistant. It was one of the secrets of efficient detection.

‘You know, boss, that’s a big brutal knife, all right, and it could have done the job, but anyone who did all that damage with just three swipes wasn’t just lashing out. We’re not just dealing with another nutter with a knife here, but with someone with real weapons skills.’

‘Aye, but that doesn’t stop him being a nutter as well!’

An hour later, after easing an account of the discovery of the body from WPC Ross, who had begun to react at last to the horror, Skinner led Martin out of the Close on to the High Street. It was 8.10 a.m., the sun had risen behind grey watery clouds, and the morning traffic was building up. Buses boomed past, their wheels roaring on the ancient cobbles.

Weatherproofed office workers bustled grimly through the drizzle. Some were heading for the Lothian Regional Council headquarters, a building so out of synchronicity with the rest of the historic street that most Edinburgh citizens try to forget that it is there. Others walked purposely towards the magnificently domed Head Office of the Bank of Scotland which overlooks Princes Street from its perch on the Mound, and is dominated in its turn by the mighty Castle, secure on its great rock.

‘Come on, Andy. Let’s go across and see if Roy Thornton’s in yet.’