Nelson says suddenly, 'You're sure about the date?'

'I'm pretty sure about the torque, that's definitely Iron Age and it seems logical that the body was buried with it.

But we can do carbon 14 dating to be sure.'

'What's that?'

'Carbon 14 is present in the earth's atmosphere. Plants take it in, animals eat the plants, we eat the animals. So we all absorb carbon 14 and, when we die, we stop absorbing it and the carbon 14 in our bones starts to break down. So, by measuring the amount of carbon 14 left in a bone, we can tell its age.'

'How accurate is it?'

'Well, cosmic radiation can skew the findings – sun spots, solar flares, nuclear testing, that sort of thing. But it can be accurate within a range of a few hundred years. So we'll be able to tell if the bones are roughly from the Iron Age.'

'Which was when exactly?'

'I can't be that exact but roughly seven hundred BC to forty-three ad.'

Nelson is silent for a moment, taking this in, and then he asks, 'Why would an Iron Age body be buried here?'

'As an offering to the Gods. Possibly it would have been staked down. Did you see the grass around the wrist? That could have been a rope of some kind.'

'Jesus. Staked down and left to die?'

'Well maybe, or maybe it was dead before they left it here. The stakes would be just to keep it in place.'

'Jesus,' he says again.

Suddenly Ruth remembers why she is here, in this police car, with this man. 'Why did you think the bones might be modern?' she asks.

Nelson sighs. 'Some ten years ago there was a child that went missing. Near here. We never found the body. I thought it might be her.'

'Her?'

'Her name was Lucy Downey.'

Ruth is silent. Having a name makes it all more real somehow. After all, hadn't the archaeologist who discovered the first modern human given her a name? Funnily enough, she was called Lucy too.