When they arrived at the villa they found Horst exercising on the lawn in a pair of swimming trunks, his body glistening with oil. He struck several dramatic poses, his flesh bulging unnervingly, before retrieving a towel from where it was draped over a statue that James hadn’t noticed before.

It was ancient and worn but it unmistakably showed a man plunging a sword into the neck of a bull, exactly like in the painting he had seen in the chapel in Eton.

‘What’s that statue?’ he asked.

‘It is Roman,’ Victor explained. ‘It was dug up when we were building the villa. It seems there might have been a Roman villa here at one time, though we could find no other evidence.’

‘Who is the man?’ said James, gently running his hand over the yellow stone.

‘Not a man, a god. Mithras.’

‘Mithras? Was he a Roman god?’ asked James.

‘In the last days of the republic the Romans were threatened by pirates,’ said Victor. ‘They would capture ships and ransom the rich men and women on board. They followed the example of the Romans and became organised, joining together into an underground movement that spread terror through the whole of the Mediterranean. They had kings and they called their men soldiers, but they operated in secret, and like any secret society they had their secret rituals. They worshipped Mithras, originally a Persian god. And to join the cult you would have to endure the pit of pain and drink the blood of bulls.’

‘What happened to them?’ said James.

‘In the end their empire was destroyed,’ said Victor, ‘but not their god. He slowly became a Roman god; the chief Roman god before Christianity took hold. He is a great favourite of Poliponi, especially since we found the statue here. He saw it as a sign. Come, I will show you something.’

Victor led James indoors and down one of the tentacle corridors to a small round room with a window in the ceiling. Hanging on the wall was one of Poliponi’s paintings in an oval frame. It showed a man dressed similarly to the carving of Mithras. He was bursting from a giant egg, holding a sword and a flaming torch. Around the frame were the twelve signs of the zodiac.

‘This is the birth of Mithras,’ said Victor. ‘He is emerging from the cosmic egg. After that, he had many adventures before slaying the primeval bull and releasing its life force for mankind. Where his blood hit the ground all good things sprang up – plants and herbs, vines and animals. He is also associated with the stars and astrology. He appeals greatly to Poliponi, who has a love of magic and mystery and is a great follower of the zodiac.’

‘Does anyone still worship Mithras?’ said James.

‘Oh, wherever there are secret societies they will have their little rituals,’ said Victor.

‘I wonder,’ said James. ‘Have you ever heard of the Millenaria?’