Rather than pause on the murder landing, Clarke and Fox hauled themselves up a further storey to the top floor. It was brighter up here, thanks to a large skylight. Just the two doors, one dark blue and the other yellow. Clarke rang the first bell, then crouched to peer through the letter box. From what she could see, the place was furnished, but without showing much sign that anyone actually lived there. The yellow door further along had no bell, just a traditional knocker. She tried it and stepped back. The door was opened by a woman in her seventies or eighties, a cat draped across her shoulders. A faint smell of litter box wafted out onto the landing. The cat’s owner hadn’t stinted with the make-up this morning – applied with more enthusiasm than skill – and was dressed in frilled, colourful layers.

‘I’ve already given a statement,’ she said in a refined Edinburgh accent. Clarke had a sudden image of girls’ schools and spinster teachers.

‘Just wanted to ask about next door,’ Clarke said. ‘It’s a rental, yes?’

‘I suppose so. Nobody seems to stay very long. Last couple of faces were tourists, I think.’

‘Have you ever seen a young woman use it?’

‘Not too tall,’ Fox added. ‘Slim, with dark spiky hair.’

‘Sounds like the daughter.’ She noted their lack of comprehension. ‘The owners’ daughter.’

‘The owners being …’

‘The Mackenzies – QC Lettings. Cheeky lot put a note through my door a while back asking if I was thinking of selling. But we like it here just fine, don’t we, Horatio?’ She gave the cat’s forehead a stroke. ‘Or we did until the tram works arrived.’

‘How do you know the Mackenzies’ daughter, if you don’t mind me asking?’

‘She shows tenants around.’ She pursed her lips, and Clarke sensed there was more.

‘And?’ she prompted. It was all the encouragement the woman needed.

‘Well, I’m not one to talk, but she sometimes uses that flat,’ she nodded towards the door next to hers, ‘or the one downstairs – you know, where it happened – when she needs to … let her hair down, shall we say.’ She took a deep breath. ‘I’ve never complained, though Mr Arbuthnot on the first floor has. Mind you, he’s never not complaining about something.’

‘His complaint in this instance being …’

‘The front door banging at all hours. Loud music and whoops and squeals. You know, young people having a bit of fun. We were all that way at some time, weren’t we?’

Clarke tried not to look at Fox. ‘We were,’ she confirmed.

‘Did you know the victim at all?’ Fox asked, shifting his feet.