‘A bit. But I couldn’t snoop about the place. I didn’t want her to turn up suddenly and catch me at it. I’d have been out of a job definitely then.’

‘Even so, you’re an observant man, I’m sure. It would be hard to spend time at Bain House, as you did, and not notice anything.’

‘OK, there might be something that occurs to me. But I can’t imagine how it would be of any use.’

Hitchens smiled at him. ‘You’d be surprised. The smallest thing might be significant.’

‘All right. Well, like you said, I’ll give it some thought.’

‘By the way, we’ll need to take your fingerprints, sir.’

‘Why?’

‘For elimination purposes.’

‘I don’t know what that means.’

‘Well, since you visited Bain House several times, your prints will be there. We need to know which ones are yours, so we can discount them.’

‘Oh, I see. All right.’

Cooper looked at the work he was doing on the wall. ‘Did you say this house belongs to your sister?’

‘No, I just said she lives here.’

‘Who does she live with?’

Grice leaned towards him in a conspiratorial manner.

‘Can you keep a secret?’

‘Yes.’

He leaned a bit closer. ‘So can I.’

Brian Mullen hesitated for a long time outside the front door of number 32. Fry gave him space. She reminded herself that it was the first time he’d seen his home since the fire; in fact, the first time he’d seen it in daylight since he left the house for a night out with Jed Skinner.

‘Take your time, sir.’

‘I’m all right.’

Mullen seemed to regard her consideration as a spur to action. He stepped forward, and was guided into the house via the approach path, through the plastic tape marking the boundary of the crime scene. He almost stumbled in the hallway, as if he was suddenly lost and didn’t know which doorway to turn into.

Fry wondered if he even recognized the place as his own home. There was almost nothing left of the original décor now. The wallpaper was blackened, the furniture charred embers. Items that would have been familiar to Mullen had been removed completely during the forensic examination. Instead, the rooms contained these strange, colourful little displays. Crime-scene flags and disposable photo markers, dozens of white squares with reference codes written on them. The old film set was in the middle of being transformed for a new production.

One of the SOCOs went by carrying another pack of markers. Had they used a hundred in here already? Fry watched him unpack the flat, heavy-duty card, folding and locking the pieces into shape for use with the flags.

‘There were some toys and other items near the source of the fire,’ she said. ‘Could you identify them for us, sir?’

Fry showed him the photographs and the exact locations where the items had been found. They included the melted Barbie doll and the remains of the PlayStation console. Then there was the blackened Monopoly board – charred piles of fake money, and red and green blobs that had once been hotels and houses.

She knew this would be painful for him. But Mullen did as he was asked, fingering the photos as if they were mementoes of a holiday he vaguely remembered. He stood in the middle of the sitting room, balancing uneasily on the stepping plates because he’d been told not to touch anything or stand on the carpet.

‘I’ve never seen this before,’ he said.

‘What is it, sir?’

He tapped one of the photographs with a finger. ‘This thing. It looks like a kangaroo.’

Fry took it from him and checked the scene inventory.

‘It was logged in as a wooden dinosaur.’

‘It doesn’t belong here.’

‘Are you sure? It’s been damaged by the fire.’

‘A wooden dinosaur, you say?’

‘According to the crime-scene examiners, it’s made from varnished walnut, with leather ears. It would have stood about six inches tall in its original condition.’

Mullen shook his head. ‘No, the kids didn’t have anything like that. They were more into PlayStations and video games. Well, Luanne had her baby toys, too. But wooden dinosaurs? No.’

‘So where did it come from?’

‘I couldn’t tell you.’ He looked at the photos again. ‘Where would you buy this kind of thing?’

‘Who else might be in the habit of buying toys for your children?’

‘Their grandparents, of course. Or my brother-in-law, John. He and Lindsay saw a lot of each other – John might have picked the thing up somewhere, I suppose.’

Fry put the photos back in the file. The toy wasn’t important, really. Many fathers would be vague about what their children played with.

‘Let’s leave that for a moment then, sir. Just walk this way, would you? And mind where you tread. Stick to the stepping plates.’

Offering up a small piece of information seemed to have given Mullen confidence. At least he was doing something positive.

‘What do you want me to see now?’

‘The hallway, sir. The hallway is important. Although the fire started in the sitting room, it was the smoke filling the hallway and rising up the stairs that caused the real problem.’

‘I know about this. I tried to get into the house, if you remember. The smoke was so bad that I couldn’t see anything, or even breathe.’

‘Quite right. If the firefighters hadn’t pulled you back, you might well have been more seriously injured.’

‘So what do you want to know?’

‘I was wondering who left the door open from the sitting room into the hall. That was what provided enough air for the fire to get a hold. It was also what allowed the smoke to spread through the rest of the house. If the fire had been contained in the sitting room a bit longer, the alarm might have been raised soon enough for lives to be saved.’

Mullen said nothing, but stood gazing at the stairs. Behind him, his family liaison officer appeared, grimacing at Fry. But she took no notice.

‘Were the doors downstairs normally left closed at night, Mr Mullen?’

‘Which doors?’

‘From the sitting room to the kitchen, for example?’

‘Yes.’

‘And what about this door, the one into the hall?’

‘Well, maybe. But Lindsay might have left that one open. She sometimes did, if I was out. She knew I’d close it when I came home and went to bed. Only I didn’t …’

‘I know. I’m sorry if this distresses you, sir. Just one last thing. Were you aware of anyone hanging around near the house in the days before the fire? Did any of the neighbours mention someone asking questions about you and your family?’

‘No, nothing like that.’

Fry nodded at the liaison officer, who came forward and put an arm round Mullen’s shoulders.

‘I tested the smoke alarm every month,’ said Mullen, with some difficulty.

‘By pressing the button?’

‘Yes.’

‘Did you realize that it only tests the sound of the alarm, not whether the detector itself is functioning?’

Mullen looked paler than ever. ‘No, I didn’t know that.’

Fry watched him for a few moments, but felt no nearer to getting inside his mind.

‘I’ll give you a lift to Darley Dale,’ she said. ‘That’s where you want to go, isn’t it?’

‘Yes, to my parents-in-law.’

When she’d got him in the car, Fry let him sit quietly for a while as they drove across Edendale. Many people would feel uncomfortable with the silence and want to make conversation. But not Brian Mullen. She left him to stew until they were out of town and heading towards the A6.

‘Tell me about the arguments you’d been having with your wife,’ she said.

‘What arguments?’ said Mullen.

‘According to your neighbours, there had been several rows between the two of you in recent weeks.’

He shook his head. ‘We had a row about the new carpet, that’s all. I didn’t think it was the most practical thing with three kids in the house. And I didn’t like the idea of Henry buying things for us all the time, either. I told Lindsay I could support my own family without his help.’