‘And, before you know it, sacrifice has become an annual ritual. But the thing is, to most people those beliefs are just superstition. We might go through certain rituals ourselves, but we don’t really believe in them. Touching wood, crossing our fingers, throwing salt over our shoulders …’

‘Counting magpies? Horseshoes nailed to the door?’

‘Exactly. It’s important to find ways of warding off evil in our lives. If you get it wrong, or upset the spirits, all kinds of bad things can happen. That’s what people believe.’

And screaming skulls, he thought. They could ward off evil, too – provided you treated them right. Cooper recalled touching the yellow sheath of bone at the back of the skull recovered from Tom Farnham’s garage. It had been cool and smooth, worn thin by age – and by reverent handling.

Most importantly, they were supposed to be left where they belonged. You should never move a skull.

‘None of these women seem to have stayed very long at Pity Wood,’ said Fry. ‘One minute they were there, the next they were gone. Perhaps they didn’t like sharing the house with preserved body parts. I can’t blame them.’

‘The Slovak, Nadezda Halak – have you got her photograph there?’

‘Yes.’

‘She’s smiling, isn’t she?’ said Cooper.

‘Some people do. It means nothing. You have to look more closely.’

Cooper squinted and studied the picture again. ‘No. She still looks happy.’

He put the photo down on his desk, and he sat looking at it for a few minutes after Fry had left.

Yes, Nadezda Halak did look happy. So what? She’d been one of those people who managed to keep smiling through the worst times of their lives. It seemed extraordinary that someone could smile and smile, and yet be so desperate. But it happened. It was as if they feared a word of sympathy or concern would crack their world apart, and only a smile could hold it together. That smiling façade became a defence, a wall to keep out the world and prevent anyone intruding into their secret misery. But why had no one been close enough to Nadezda to see behind that smile?

Then Cooper thought of something he’d meant to ask. ‘By the way, Diane, you’re not leaving, are you?’

To his astonishment, she grabbed his sleeve roughly. He flinched at the sudden awareness of her potential for violence. He knew it was in her, but he saw it so rarely that he’d managed to forget.

‘What do you know?’ she hissed.

‘Nothing. It was just something Gavin said. Gossip probably.’

‘Was anything said about me while I was in Ireland?’

‘No, Diane. Well, not that I’m aware of. You know I’m the last person to find out anything.’

She let go of his sleeve. ‘That used to be true. I’m not sure any more.’