The smell in Jack’s rooms was as musty and rich as ever. A mortar lay on a table, with some sweet-smelling herb half crushed inside it. An astrolabe was placed down to one side, as if Jack had just finished with it. There were many other things that, in other circumstances, Tom would have enjoyed looking at. The glass structure caught him off guard once more, and he stared at it, seeing both himself and Jack reflected in its surface. The way that Tom was standing his body seemed to cover Jack’s entirely, and it was as if their faces merged together. Startled, Tom moved away.

Jack heaved a sigh. ‘I will show you. What we have. What I, James Swinton, have. What you will have when I choose to go.’

‘Why don’t you free the Captive?’ Tom spoke through his teeth.

The question made Jack turn and gaze at him, as if it had never occurred to him before. He spoke slowly, as if to a child. ‘The moment I free her, she will kill me and you, and there will be a storm such as has never been seen.’ He paced to the window. It was bright outside. ‘Do you think they are like us? Do you think that because they look human that they are human?’ He chewed his lips reflectively. ‘They do not exist like us, think like us, eat like us. Their minds span centuries. We are nothing to them. They would squash us as we would a fly. Umbra sumus, Thomas. We are shadow. They are not. I thought they were of the divine essence. In past times I thought I was talking to angels. But they are not angels. They are something else.’

‘What are they?’

Jack smirked. ‘I do not know, but I worked long and hard to understand them.’

‘Why don’t they attack?’

‘They cannot touch me. What I have done is unprecedented.’ He studied Tom for a second. ‘I have kept one of them and I have partaken in their essence. They tell me – Zita, Kit – that it has been four hundred years. To me – I have flown further and seen more. Sometimes it seems like a thousand years. Sometimes like the passing of a cloud in front of the sun. What am I but a mayfly on the surface of the stream? What am I but a pebble dropped into an ocean? Come.’ He took Tom’s wrist and held his hand gently, pulling him downwards to sit with him on a low brocaded sofa.