Cooper laughed, and gestured at the hills on all sides. ‘Limestone? This is the White Peak. Everything is limestone here.’

‘Yes,’ said Robertson doubtfully. ‘Of course, we only have the word of Pliny the Elder. Pliny said limestone could consume a body in forty days. Personally, I wouldn’t rely on it too much as a forensic theory.’

As Fry lifted the latch on the churchyard gate, she turned towards them, and Cooper saw that her face was set into an expression of impatience and scorn.

‘Thank you for the history lesson, Professor,’ she said. ‘I’m sure you’ve improved DC Cooper’s education immensely. He’ll be a much better detective from now on.’

Fry moved off towards the car, but Robertson touched Cooper’s sleeve to hold him back as they reached the gate.

‘There’s one more word that I’m sure you know,’ said the professor.

‘What’s that, sir?’

‘Sarcasm. Another figurative expression handed down to us from the Greek. It means tearing or biting at the skin, like an animal. The Greeks didn’t like sarcasm very much.’

Fry was waiting by the Toyota, tapping her fingers on the roof as she watched people walking by on the street. Cooper unlocked the car, and she slid quickly into the passenger seat.

‘Oh yes, we doctors do so love our Latin and Greek,’ she said, fastening her seat belt. ‘It’s so, so fascinating – but only for those with a little knowledge of the classical world. Not for the ignorant plebs who studied useful subjects, instead of some ancient dead language.’

‘Diane …’

She looked at him with irritation. ‘A real bloody Aristotle we’ve got there, haven’t we? I bet he can’t get in the bath without jumping out again and shouting “Eureka!”’

‘I think that was Archimedes,’ said Cooper, waving to Freddy Robertson as they pulled away from the church. Standing by his BMW, the professor gave a little bow.

Fry stared out of the window at the streets of Edendale.

‘Lawyers are just the same. Why do these people have to make their jobs sound like some kind of arcane mystery the rest of us couldn’t possibly understand?’

‘Maybe it’s insecurity …’ Cooper paused. ‘Why didn’t you let me listen to the tape of the phone calls before I went to see the professor?’

‘You never asked.’

‘It would have helped a lot. As it was, I only had partial information.’

‘Yes, OK, Ben.’

The BMW closed up behind them as they stopped at the traffic lights before the relief road.

‘Those sarcophagi he showed us,’ said Fry. ‘They’re not even in our target area.’

‘Yes,’ said Cooper. ‘I know.’