Dr Frazer Theobald was making his usual slow but thorough progress. His examination of the dead woman’s stomach indicated she had not eaten in the immediate hours before she was killed, which would give some help in gauging when she might have died – early in the evening rather than late, if she had not had an evening meal. There was no smell of alcohol either – which would have been present after just a couple of drinks – which meant it was unlikely although not impossible that she had been to a bar.

Shortly after half past twelve, when Grace stepped away again, this time to call Dennis Ponds to check on the 2 p.m. press conference, Glenn Branson walked over to him, looking uncharacteristically shaken and bilious.

‘You’d better come and look at this, Roy.’

Grace killed the call he was about to make and followed him across the room. Everyone was standing around the table in what looked to him like shocked silence. As he approached he could smell the vile stench of excrement and bowel gases.

The woman’s torso had been opened up, her ribcage was exposed and he could see that her heart, lungs and the rest of her vital organs had been removed, and lay waiting to be bagged and put back inside her chest when the post-mortem was finished, leaving an empty carcass.

On the metal-edged dissecting tray, raised some inches above her, was a length of pale brown tube which looked like a long sausage. It was about an inch in diameter, lying in a mess of blood, excrement and mucus. Dr Theobald had made an incision in it, which he was holding open with forceps for everyone’s benefit.

The pathologist turned to him, his moustachioed face even more serious than usual. Then he pointed. ‘I think you should take a look at that, Roy.’

Anatomy had never been Grace’s strong point, and sometimes when peering at the organs of a cadaver it took him some time to orient himself and figure out what was what. He looked down, trying to work out what this might be. Part of the intestines, he thought. Then, as he was looking, Dr Theobald used the forceps to open the incision he had made further, and now Grace could see something in there.

Something that everyone else in the room had already seen.

Something that made him stare, for some moments, in complete, mind-boggled shock.

Then he took an involuntary step back as if he wanted to get away from it.

‘Jesus,’ he said, closing his eyes for an instant, feeling the blood draining from his head. His stomach was boiling in shock and revulsion.

‘OhmyGod.’

It was a shiny, fat, black beetle, two inches long, with spiny feet and a ribbed back, and it had a single curved horn protruding from its head.

Frazer Theobald picked it up, delicately, with a pair of tweezers and held it aloft for all to see. The creature was motionless.

Grace who had never cared for beetles, took another step back. In truth he was not good at creepy-crawlies in general; he had been scared of spiders all his life and was very definitely wary of beetles. And this was – oh Jesus – one seriously horrible-looking creature.

He caught Cleo’s eye and saw a flash of revulsion in her face.

‘That’s what, exactly?’ Branson said, his voice quavering, pointing down at the dissecting table, involuntarily rescuing Grace from asking a potentially dumb question.

‘Her rectum, of course,’ the pathologist said dismissively.

Branson turned away, looking repulsed. Then he watched as Theobald brought the beetle towards his nostrils, the long fronds of his moustache twitching, close to becoming entwined in the hair-like spines on the beetle’s legs.

The pathologist sniffed deeply. ‘Formaldehyde,’ he announced. Then he proffered the insect to Grace for verification. The Detective Superintendent fought his revulsion and sniffed also. Instantly he caught the whiff that reminded him of his school biology dissection classes.

‘Yes,’ he agreed. Then he looked down again at the dissection table.

‘That’s why I didn’t detect it on a visual examination of the rectum – it had been inserted too far up.’

Grace stared at the neck of the tube on the table, the dead young woman’s sphincter. ‘In your view, Frazer, inserted before or after her death?’

‘I can’t tell.’

Then he asked the question that was on everyone’s lips. ‘Why?’

‘That’s for you lot to figure out,’ Theobald said.

Branson was standing on the far side of the room, leaning against the work surface adjoining the sink. ‘Remember Silence of the Lambs?’

Grace remembered it well. He had read the novel, one of the few books that had genuinely scared him, and had seen the film.

‘The victims all had a moth stuffed down their throats,’ Branson said. ‘It was a death’s head moth.’

‘Yes,’ Grace said. ‘It was the killer’s signature.’

‘So maybe this is our killer’s signature.’

Grace stared at the beetle, which the pathologist was still holding aloft. He could swear for an instant that its legs were twitching, that the thing was still alive. ‘Anyone know what kind of beetle it is?’ he asked.

‘A stag beetle?’ Cleo Morey suggested.

‘Not with that horn.’ Darren, the Assistant Mortician interjected. ‘I studied entomology as part of my course. I don’t remember anything like that in the UK. I don’t think it’s native.’

‘Someone’s imported it?’ Grace said. ‘They’ve gone to the trouble of importing it, then inserted it up her rectum? Why?’

There was a long silence. Finally the pathologist inserted the insect in a plastic bag and labelled it. ‘We need to find out all we can about it,’ he said.

Grace was thinking hard. Over the years he had from necessity read as much as he could find on the mentality of murderers. Most murders were domestic, perpetrated by people who knew their victims. These were one-offs, frequently crimes of passion committed in the heat of the moment. But a small percentage of murderers were the truly warped ones who killed for gratification and thought they could outwit the police – sometimes to the extent of playing games with them.

These were the killers who often left some kind of signature. A taunt. This is my clue; catch me if you can, you dumb mother of a cop!

Grace looked at his watch. There was one person he knew who could tell him, probably instantly, what kind of beetle this was. Whether that would be of any real help or not, he had no idea, but just maybe it would yield a clue.

‘We need to keep this from the press,’ he said. ‘Total radio silence on this, everyone, OK?’

All nodded. They understood his reasoning. With a clue as unusual as this they would know instantly that if a caller claiming to be the killer could describe this, he was their man. It could save them hours, if not days, of sifting through false leads.

Grace told Branson to get one of the team at the Incident Room to trawl the UK for any other murder victims where there had been a beetle found at the scene. Then he asked the pathologist a stupid question. He knew it was stupid, but it still needed to be asked. ‘The beetle was definitely dead before it was inserted?’

‘I doubt anyone would keep a supply of formaldehyde up their rectum,’ the pathologist replied, just very slightly sarcastically. He pointed at a small glass vial on the dissecting tray which contained a murky-looking fluid. ‘There is no trace in there – that’s the bowel lining mucus.’

Grace nodded and did a quick mental calculation. If he left straight after the press conference there would be time to show the beetle to the one man he was certain would be able to identify it.