The wonder of it was that the neighbours hadn't complained, hadn't even – as many of them later told the newsmen -realized. Not until that night, the night their sleep was disturbed by sudden activity in the street. Cars, vans, policemen, the static chatter of radios. Not that the noise ever got out of hand. The whole operation was directed with such speed and, yes, even good humour that there were those who slept through the excitement.

I want courtesy,' Chief Superintendent 'Farmer' Watson had explained to his men in the briefing room that evening. 'It may be a hoor-hoose, but it's on the right side of town, if you take my meaning. No telling who might be in there. We might even come across our own dear Chief Constable.'

Watson grinned, to let them know he was joking. But some of the officers in the room, knowing the CC better than Watson himself apparently did, exchanged glances and wry smiles.

'Right,' said Watson, 'let's go through the plan of attack one more time

Christ, he's loving this, thought Detective Inspector John Rebus. He's loving every minute. And why not? This was Watson's baby after all, and it was to be a home birth. Which was to say, Watson was going to be in charge all the way from immaculate conception to immaculate delivery.

Maybe it was a male menopause thing, this need to flex a bit of muscle. Most of the chief supers Rebus had known in his twenty years on the force had been content to push pens over paper and wait for retirement day. But not Watson. Watson was like Channel Four: full of independent programmes of minority interest. He didn't make waves exactly, but by Christ he splashed like hell.

And now he even seemed to have an informer, an invisible somebody who had whispered in his ear the word 'brothel'. Sin and debauchery! Watson's hard Presbyterian heart had been stirred to righteous indignation. He was the kind of Highland Christian who found sex within marriage just about acceptable – his son and daughter were proof – but who baulked at anything and everything else. If there was an active brothel in Edinburgh, Watson wanted it shut down with prejudice.