Before the action moved outside, Cooper took a chance to study the interior of the house. One of the first things that had struck him was the amount of dust. Of course, there had been no cleaner. And Miss Shepherd had only done the minimum amount of housework herself, by the looks of it. A bit of attention to the sitting room, the kitchen, the bathroom, and her bedroom.

But there were other rooms that seemed to have lain untouched. Opening the door into a guest bedroom set balls of dust rolling across the carpet, spiders scurrying away from the movement. The curtains were closed in here, so Cooper switched on the light. Fine particles of dust hung in the air, swirling in the draught from the landing.

Most people had no idea where the dust in their homes came from. As far as the average householder was concerned, it might as well come from the Moon, floating down from the sky every night and settling on available surfaces like drifting snow. An inconvenience, perhaps, but something natural and inert that was just part of the atmosphere, like oxygen.

But Cooper knew different. It was one of those facts that he’d learned as a teenager and never forgot. He knew that all human beings in the world shed thousands of dead skin cells every hour, an entire layer of skin over three days. That was what hung in the air and danced in a shaft of sunlight from the window. That was what lay on the shelves and gathered in restless clumps under the bed, or shrouded the junk in the attic. Ninety per cent of the dust in any house consisted of dead human skin.

Also, the décor in the sitting room struck him as odd. Off-white and charcoal grey, almost no colour. It seemed a bit modern for a house of this age, let alone for the sort of woman that Rose Shepherd seemed to have been. As far as anyone could tell, anyway.

Hitchens stuck his head round the door. ‘Ben, we’ve brought the postman back to the scene. Go and get a statement from him, will you? He’s fretting about getting back on his rounds.’

‘Right, sir.’

Cooper took a last look at the charcoal grey wallpaper around the fireplace. It showed up the dust badly, and it was undisturbed by finger marks. And then he remembered another fact he’d learned about house dust. Each speck of it carried tens of thousands of dust mites. Right at this moment, they were busy feeding on those dead skin cells.

Chapter Six

Chapter Six

‘Years ago, I used to work on a delivery round out Leek way,’ said Bernie Wilding when Cooper found him sitting in his red mail van. ‘I saw those wallabies out there about as often as I saw Miss Shepherd in Foxlow.’

‘The wallabies?’