Then she said simply, ‘I’m sorry, but I don’t understand. Why would anyone want to kill Crabby?’

Stone withdrew his phone from his pocket. Flicking through the pictures, he turned it through one hundred and eighty degrees and showed an image to Jo. ‘Do you recognise this?’

Jo gestured towards the phone. ‘May I?’

‘Go ahead.’

She zoomed into the image, swiping her finger up and down the screen.

She passed him back the phone. ‘It’s a context sheet.’ He looked puzzled. ‘One of the recording forms that we use on the dig. Like these.’

She plucked a ring binder from the shelf and flipped it open to show him. He nodded.

Then Jo added, ‘It’s not one of ours, though. That’s Beth’s handwriting. But there’s something not right with it.’

‘Oh, why’s that?’

Jo said, ‘In the section about finds down at the bottom it says that layer had a fragment of stone tablet in it. And there’s been nothing like that found on the excavation.’

‘Are you sure?’

‘One hundred per cent. If there’d been anything like that found we’d have it here with the rest of the finds.’ Jo opened the lid of the laptop sitting in front of her, pulled up a database and searched for the word ‘tablet’. ‘And there’s nothing in the finds register – see. Do you mind if I ask where it came from?’

He sighed. ‘We found it in Mr Crabbs’ house. It was sitting in an empty shoebox on his coffee table. It appeared to have been wrapped around something. But whatever it was wasn’t there any more. There was one more thing.’ He scrolled through the pictures on his phone again. ‘This was found lying next to Mr Crabbs.’

Jo took the phone. It was the image of a large black bird. A small photographic scale had been positioned alongside it. She was no ornithologist, but just by the size of it she could tell what it was.

She placed the phone down on the table. ‘I’m guessing you already know it’s a raven.’ He nodded. ‘Ravens were sacred birds in Celtic mythology, DCI Stone, and it’s not uncommon to find them in offering pits. Sometimes on their own, sometimes with other animals. But the other stuff – the head and the throat and that twine – it’s what they call the threefold or triple death.’

‘The what?’

‘The triple death. It’s what they would do in the Iron Age on the rare occasions that they sacrificed people. A blow to the head, a garrotte and then finally they severed the jugular vein. Some people think the blow to the head was a sort of mercy blow to knock them unconscious. The garrotte was almost certainly supposed to increase the blood flow when the throat was cut.’

Stone offered a grim, weary smile. ‘I’m glad they didn’t make a habit of it.’