‘Well, you’ve had a drink, haven’t you? Might not be the best time for a house call … sir.’

‘You’re probably right … Paddy,’ Rebus said, making for the door.

‘Remember what you asked me?’

Rebus had accepted a black coffee from David Costello. Popped two paracetamol from their foil shroud and washed them down. Middle of the night, but Costello hadn’t been asleep. Black T-shirt, black jeans, bare feet. He’d made an off-licence run at some point: the bag was lying on the floor, the half-bottle of Bell’s sitting not far from it, top missing but only a couple of decent measures down. Not a drinker then, Rebus surmised. It was a non-drinker’s idea of how you handled a crisis – you drank whisky, but had to buy some first, and no point lashing out on a whole bottle. A couple of drinks would do you.

The living room was small, the flat itself reached from a turreted stairwell, winding ever upwards, the stone steps worn concave. Tiny windows. They’d planned this building in a century where heat was a luxury. The smaller the windows, the less heat you lost.

The living room was separated from the kitchen only by a step and what looked like partition walls. An open doorway, double-width. Signs that Costello liked to cook: pots and pans hanging from butcher’s hooks. The living area was all books and CDs. Rebus had trawled the latter: John Martyn, Nick Drake, Joni Mitchell. Laid-back but cerebral. The books looked like stuff from Costello’s English Literature course.

Costello was seated on a red futon; Rebus had chosen one of two straight-backed wooden chairs. They looked like the stuff he saw on Causewayside, placed outside shops for which the description ‘antique’ encompassed school desks from the sixties and green filing cabinets salvaged from office refits.

Costello ran his hand through his hair, didn’t say anything.

‘You asked if I thought you did it,’ Rebus said, answering his own question.

‘Did what?’

‘Killed Flip. I think that’s how you phrased it: “You think I killed her, don’t you?”’

Costello nodded. ‘It’s so obvious, isn’t it? We’d fallen out. I accept that you have to regard me as a suspect.’

‘David, right now you’re the only suspect.’

‘You really think something’s happened to her?’

‘What do you think?’

Costello shook his head. ‘I’ve done nothing but rack my brains since this all started.’

They sat in silence for a few moments.

‘What are you doing here?’ Costello asked suddenly.

‘As I said, it’s on my way home. You like the Old Town?’

‘Yes.’

‘Bit different from the New. You didn’t want to move nearer Flip?’

‘What are you trying to say?’

Rebus shrugged. ‘Maybe it says something about the pair of you, the parts of town you prefer.’

Costello laughed drily. ‘You Scots can be so reductive.’

‘How’s that?’