Watch had been kept for several days and nights, courtesy of unmarked cars and unremarkable plainclothes men. Until there could be little doubt: whatever was happening inside the shuttered rooms, it was happening after midnight and it was happening briskly. Interestingly, few of the many men arrived by car. But a watchful detective constable, taking a leak in the dead of night, discovered why. The men were parking their cars in side streets and walking the hundred yards or so to the front door of the four-storey house. Perhaps this was house policy: the slamming of after-hours car doors would arouse suspicion in the street. Or perhaps it was in the visitors’ own interests not to leave their cars in broad streetlight, where they might be recognized . . .

Registration numbers were taken and checked, as were photographs of visitors to the house. The owner of the house itself was traced. He owned half a French vineyard as well as several properties in Edinburgh, and lived in Bordeaux the year through. His solicitor had been responsible for letting the house to a Mrs Croft, a very genteel lady in her fifties. According to the solicitor, she paid her rent promptly and in cash. Was there any problem . . .?

No problem, he was assured, but if he could keep the conversation to himself . . .

Meantime, the car owners had turned out to be businessmen, some local, but the majority visiting the city from south of the border. Heartened by this, Watson had started planning the raid. With his usual blend of wit and acumen, he chose to call it Operation Creeper.

‘Brothel creepers, you see, John.’

‘Yes sir,’ Rebus answered. ‘I used to own a pair myself. I’ve often wondered how they got the name.’

Watson shrugged. He was not a man to be sidetracked. ‘Never mind the creepers,’ he said. ‘Let’s just get the creeps.’

The house, it was reckoned, would be doing good business by midnight. One o’clock Saturday morning was chosen as the time of the raid. The warrants were ready. Every man in the team knew his place. And the solicitor had even come up with plans of the house, which had been memorized by the officers.

‘It’s a bloody warren,’ Watson had said.

‘No problem, sir, so long as we’ve got enough ferrets.’

In truth, Rebus wasn’t looking forward to this evening’s work. Brothels might be illegal, but they fulfilled a need and if they veered towards respectability, as this one certainly did, then what was the problem? He could see some of this doubt reflected in Watson’s eyes. But Watson had been enthusiastic from the first, and to pull back now was unthinkable, would seem a sign of weakness. So, with nobody really keen for it, Operation Creeper went ahead. While other, meaner streets went unpatrolled. While domestic violence took its toll. While the Water of Leith drowning still remained to be solved . . .

‘Okay, in we go.’