Holmes took them in his two hands, and jerking Fricano forward examined them closely. The man winced in pain. ‘Ah! Yes, burns!’ said Holmes. He dropped Fricano’s hands. The man backed away, affronted.

‘And then?’ Holmes prompted.

‘I find … I find … Oh, God,’ moaned Fricano. He covered his face with his injured hands. ‘I find Dario.’

‘Doctor? The body, now, inside the cauldron, if you please? Take a very close look.’

I moved a few feet around the sphere and spun it so that the front opening faced me and was well lit from one of the stage lights. Hamilton appeared behind me, a pocket lantern in his hand to help illuminate the interior.

While my wartime experiences had somewhat inured me to the sight of grievous injury and death, what I encountered here sickened even me. I opened the front hatch and the stench of burned flesh gagged me, but there was another smell as well, a metallic odour – not exactly paraffin, not exactly petroleum, but similar. I quickly placed my handkerchief over my nose and mouth.

Inside was an image that will forever be seared into my mind.

It was the figure of a large man, contorted into a kind of foetal position, arms raised in what is known by coroners as the pugilistic pose. The clothes, the shoes and most of his skin was burned away, leaving a shiny black coating overall. The face was unrecognizable.

I was filled with revulsion, but I had a job to do.

Gingerly, I leaned in through the opening and touched the corpse’s shoulder. A large flake of cinder fell off, leaving what looked like raw meat below. I have seen many a gruesome death, but this was a horror. I backed out to catch my breath.

‘Dear God, Holmes. The man was incinerated under some extreme and sudden heat. All the clothes and skin are gone,’ I said. I leaned in and continued my examination.

After few terrible minutes, my investigation was done. I stood next to Holmes, wiping my hands as best I could on my handkerchief. Hamilton, much affected by the sight, had followed and stood behind me.

‘An accelerant, then, Watson?’ said Holmes.

‘Definitely,’ I replied. ‘It was a kind of flash burn. Uniformly across the entire body. No one’s skin and clothes would ignite in such a way without some kind of chemical present.’

‘A petrochemical from the smell, wouldn’t you say?’

‘Perhaps. I don’t recognize the odour.’

‘Could it have been poured in from that bottle by the young lady?’

‘I would say not.’

‘Why?’

‘To get this result, you would need much, much more. And uniformly covering the body. Perhaps in some kind of gel or powder.’

‘The entire body?’ asked Holmes. ‘Prepared, then?’

‘It would appear so. That body was … soaked with it. Or painted.’

‘Death would have been instantaneous, then,’ remarked the detective.

‘We heard screams,’ said Fricano.

‘Well, very quickly then,’ said Holmes.

I shuddered. ‘Yes.’