As he made that downward journey for the third time, it seemed to Alleyn that in its quiet way it was one of the strangest he had ever taken. A monk, a lay-brother and himself, descending, if one cared to be fanciful, through a vertical section of the past.

When they reached the cloisters on the second level, Brother Dominic, who had not yet uttered, turned on the fluorescent lights and back into their immovable liveliness sprang the Apollo and the Mercury.

Down the iron spiral: two pairs of sandals and one pair of leather soles with the ever-mounting sound of flowing water. The bottom level and a right turn. This was where Kenneth Dorne had parted company with Sebastian Mailer. On their left was the little ante-room into the Mithraeum. Ahead—the lights came on—ahead, the sarcophagus and the railed well.

They walked towards them.

The lid had not been replaced. It stood on its side, leaning against the empty stone coffin where Violetta had been urgently housed.

Father Denys put his hand on Alleyn’s arm.

‘Now,’ he said and they stopped.

‘Yes,’ Alleyn said.

It declared itself: sweetish, intolerable, unmistakable.

He went on alone, leant over the top rail where he had found a fragment of cloth and looked into the well, using the torch they had given him.

It showed walls in a sharp perspective and at the bottom an indefinable darkness.

‘The other day,’ he said, ‘when I looked down, there was a sort of glint. I took it to be a chance flicker of light on the moving stream.’

‘It could be that.’

‘What is there—down below?’

‘The remains of a stone grille. As old,’ Father Denys said, ‘as the place itself. Which is seventeen hundred years. We’ve lowered a light and it revealed nothing that you could call of any consequence but it was too far beneath to be of any great help.’

‘The grille is above the surface of the stream?’

‘It is. A few inches at the downstream end of the well. And it’s the remains only. A fragment you may say.’

‘Could something have been carried down by the stream and got caught up in it?’

‘It’s never been known in the history of this place. The water is pure. Every so often we let down a wee tin and haul up a sample for the testing. There’s never been the hint of contamination in it.’

‘Can one get down there?’

‘Well, now—’

‘I think I can see footholds and—yes—

Brother Dominic spoke. ’You can,’ he said.

‘Aren’t there iron pegs?’

‘There are.’

‘And they rotten no doubt,’ Father Denys urged, ‘and falling out like old teeth at the first handling.’

‘Have you a rope, Father?’

‘Sure, we have them for the excavations. You’re not thinking—’

‘I’ll go down if you’ll give me a hand.’

‘Dominic, let you fetch a rope.’