Nor was the flat just a flat. It was ‘the flat in Edinburgh’s fashionable New Town’, the ‘quarter-million flat owned by Ms Balfour’s parents’. John and Jacqueline Balfour were ‘the numbed family’, ‘the shocked banker and his wife’. Their daughter was ‘Philippa, 20, a student of art history at the University of Edinburgh’. She was ‘pretty’, ‘vivacious’, ‘carefree’, ‘full of life’.

And now she was missing.

Detective Inspector John Rebus shifted position, from in front of the marble fireplace to slightly to one side of it. David Costello’s eyes followed the move.

‘The doctor gave me some pills,’ he said, finally answering the question.

‘Did you take them?’ Rebus asked.

The young man shook his head slowly, eyes still on Rebus.

‘Don’t blame you,’ Rebus said, sliding his hands into his pockets. ‘Knock you out for a few hours, but they don’t change anything.’

It was two days since Philippa – known to friends and family as ‘Flip’ – had gone missing. Two days wasn’t long, but her disappearance was out of character. Friends had called the flat at around seven in the evening to confirm that Flip would be meeting up with them within the hour at a bar on the South Side. It was one of those small, trendy places which had sprung up around the university, catering to an economic boom and the need for dim lighting and overpriced flavoured vodkas. Rebus knew this because he’d walked past it a couple of times on his way to and from his place of work. There was an old-fashioned pub practically next door, with vodka mixers at a pound-fifty. No trendy chairs though, and serving staff who knew their way around a brawl but not a cocktail list.

Seven, seven-fifteen, she probably left the flat. Tina, Trist, Camille and Albie were already on their second round of drinks. Rebus had consulted the files to confirm those names. Trist was short for Tristram, and Albie was Albert. Trist was with Tina; Albie was with Camille. Flip should have been with David, but David, she explained on the phone, wouldn’t be joining them.

‘Another bust-up,’ she’d said, not sounding too concerned.

She’d set the flat’s alarm before leaving. That was another first for Rebus – student digs with an alarm. And she’d done the mortise lock as well as the Yale, leaving the flat secure. Down a single flight of stairs and out into the warm night air. A steep hill separated her from Princes Street. Another climb from there would take her to the Old Town, the South Side. No way she’d be walking. But records from her home telephone and mobile had failed to find a match for any taxi firm in the city. So if she’d taken one, she’d hailed it on the street.

If she’d got as far as hailing one.

‘I didn’t, you know,’ David Costello said.

‘Didn’t what, sir?’