Murfin grunted and passed her the file. Fry had seen the photographs before she came out, and remembered the condition of Lindsay’s body, the cotton pyjamas she’d been wearing, with the left leg rucked up to expose a thin, white calf. Her face was only visible in the close-ups, turned to the right, her left cheek pressed tightly to the floor.

It wasn’t Lindsay Mullen’s face that Fry was interested in, but the position of her body, the angle of her limbs. She turned one of the photos to align it with the room, and checked the direction of the door. Lindsay had almost certainly been going the wrong way. It wasn’t too difficult to picture her, blinded and disorientated by darkness and dense smoke, feeling her way frantically round the walls in an effort to find the door, while her children screamed in the next room. It wasn’t difficult at all. In fact, it was too easy for comfort.

‘Next room, Gavin,’ she said.

‘That’s the kids’ bedroom.’

‘I know that.’

Jack and Liam Mullen had died without leaving their beds, according to the incident reports. They woke up choking, and died from the effects of smoke inhalation. Died calling for their mum, probably.

The house must have been so full of smoke by then that the boys would never have made it to the stairs, let alone through the flames in the hall. Still, their bedroom wasn’t a pleasant place to be. Gavin wouldn’t even come inside the door. He knew the bodies had lain here for some time, since the boys had obviously been dead and beyond rescue. Coroners’ rules required the bodies to be left in situ until forensic evidence had been gathered to establish the cause of death.

Of course, the vast majority of house fires were tragic accidents. Faulty wiring, a fag down the back of the sofa, clothes left too near an electric heater. If sudden deaths didn’t go automatically to CID, she wouldn’t even be here. Fire service codes on this incident were ambiguous – but then, the firefighters on the scene would have had other priorities than looking for a cause.

Fry heard a rustle and a cough, and turned to find a uniformed PC standing at the bottom of the stairs. He was wearing a yellow reflective jacket, and he held his helmet in one hand as he wiped the sweat from his forehead with the other.

‘DS Fry?’ he said, looking up at her. ‘They said you’d be here. I thought you ought to know straightaway –’

‘What is it?’

‘Well, we’ve been talking to the neighbours again. We ought to have found out earlier, I suppose, but we never thought to ask. You know what it’s like, everyone is in shock when a thing like this happens, and with the husband being taken off to hospital –’

‘Out with it, for heaven’s sake.’