We got back to the boat, Drennan screaming at the man we had left behind. Twenty seconds. Fell into it so hard that it almost capsized, the American reaching out at the same time to pull the painter loose and push the boat away from the side. Fifteen seconds. Began to row furiously, seeing the light of the day outside come closer and closer. Ten seconds. Got halfway into the normality of the canal outside, the boats laden with fruit, clothes, wood. People calling to each other, some singing. Five seconds. Then we were clear, but still heading across the canal, Drennan shouting like some lunatic at the other boats, telling them to get out of the way, keep their heads down. Two seconds. And I looked back and up, and saw Cort standing by the window, the one I had once seen open as an old man had sung below it. He rested his elbow on the sill, his chin on his hand. He looked content.

There was a tremendous explosion, followed by another and another as other charges ignited around the column. Masonry and plaster and roof tiles began flying through the air and the inside of the building was suddenly lit up by a bright red and orange light. Something like a tidal wave swept outwards across the canal; our boat capsized, and so did many others which were on our side of the palazzo. Fruit and vegetables and washing and people were flung into the water, and when I rose gasping to the surface and looked back, I could see that the entire roof and upper storeys of the building had vanished, the thin walls had collapsed like paper, falling inwards with a deafening noise, a huge cloud of dust rising above the scene, pushed upwards by the blast.

Drennan and I managed to get to our boat, which had spun round so completely it was now the right way up again, half full of water but floating. Then the masonry, flung into the air by the explosion, began crashing down into the canal like some bombardment. Enormous fountains of water erupted randomly; one boat was sunk by a piece of what looked like a chimney; windows were smashed and brickwork stoved in. People were screaming, running, lying on the ground with their heads in their hands. Our oarsman had swum for the far side, and I saw him dragging himself out of the water, pale-faced but apparently unharmed. Then I looked around. The water was littered with debris and people thrown out of the boats; men and women alike were panicking and were being rescued; I grabbed a woman who was sinking and got her to hang on to the side of our boat. Drennan and I tried to push her into it, but she was too fat, her clothes too heavy with water, and she started screaming and hitting us instead, so we stopped and began pushing her to the side. A crowd was gathering by the edge of the canal, some were jumping in to assist, others were just looking, open-mouthed at the catastrophe before them.

We said nothing; we were too out of breath, too much in shock, to say a word, but our boat eventually drifted close to the far side of the canal, and Drennan started kicking with his feet to finish the job. I helped, then we pulled ourselves round until we were within reach of outstretched arms, waiting to pull us out, and drop us on the warm stone, where we lay, panting furiously from terror and exhaustion.

Drennan recovered much faster than I, standing up shakily, and accepting a thick blanket to wrap around his shoulders. I took longer but eventually stood, my legs shaking so much I almost sank back to the ground again.

At least it didn't look as though any passers-by had been hurt; they had been given a nasty shock and a soaking, that was the extent of it. But I knew there was no hope for the other two. Nothing could have survived that; anyone inside must surely have died.

Then Drennan touched my arm and pointed. A body was being dragged from the water, and people were shouting for assistance. It was Cort. He was mortally pale, and blood had soaked the sleeve of his black coat and matted his hair, but he seemed to be alive – at least those around him seemed to think so as they were shouting for a doctor to come as quickly as possible, laying him with touching gentleness on the ground, holding his hand.

'He must have been blown through the window,' Drennan said softly.

'And Macintyre, you think?'

'No hope there. None.' He said no more, but I knew he must be right. The engineer had been lying only about two feet from the main explosive charge. That alone, quite apart from the falling masonry and fire, would have killed him instantly.

'We will be questioned by the authorities,' Drennan said quietly. 'We need to decide what we will say.'

'The truth, I imagine.'

But Drennan nodded at Cort. 'And what about him?'

I looked at Cort's poor white face and felt suddenly sick. I knelt back on the ground, and leant my forehead on the stone, trying desperately to control the violent heaving of my stomach. I failed.

Drennan dragged me upright again and shook me violently. 'Pull yourself together,' he hissed in my ear. 'We have to get away from here before the authorities arrive. We can go and talk to them later when we know what we're doing. Follow me quickly.'

No one paid much attention to us as we disappeared into a little side alley, then hurried off. I took Drennan back to the Marchesa's, where I ordered hot water from the maidservant, and insisted that it be brought immediately. Faster than immediately. Then we went to my rooms, stripped off and wrapped ourselves in towels to wait. Neither of us said a word; I slumped in a chair, conscious only of the smell of rank mud that was in my nose and my hair and all over my body. Drennan paced up and down impatiently but was no more capable of speech than I. I poured two large tumblers of Italian brandy – harsh, unpleasant stuff but strong and effective, and we drank that instead. Then another, until the water arrived, and was poured into the tin bath by the servants.

Then we were done and dressed, Drennan looking slightly baggy in a borrowed suit, for he was smaller than I.

'Listen Drennan, I have to tell you something.'

'Go ahead.'

'I do not think that what we witnessed today was Cort murdering Macintyre.'

'No?'

'I believe we witnessed Louise Cort trying to murder her husband.'

I sat down and told him, very meticulously and honestly, everything that had happened. He showed no surprise, indeed gave no reaction at all. I ended by handing him the letters which had been delivered that morning. He looked at them, and gave them back.

'I see. So you are afraid . . .'

'No. I am not afraid of her at the moment. I am afraid for the boy. The last time I spoke to her she said all she had to do was to free herself of her husband and the boy, then she would deal with me. I didn't take her seriously then, but now it worries me.'

Drennan stood up. 'Do you want me to go to his lodging and see?'

'If you're up to it, I would be very grateful. More grateful than I can say. I do not think my going would help.'

'I think that is right.'

He left, and I sent word for the Marchesa, to ask for a few moments of her time.

She heard me out impassively, then sighed sadly. 'That poor man, of course I knew such a thing would happen. His aura . . .'

'Just stop this rubbish about spirits and auras,' I snapped. 'We haven't got time. Cort has killed a man. He might be insane, but if so, it was your ridiculous séance that set him off. How is that going to look when it gets round this city, eh?'

The spirits retreated whence they came as the Marchesa realised her peril. Scandal has killed as many people as knives and bullets.

'If it was just your reputation, then I wouldn't care too much. But Macintyre had a daughter. Cort has a son. And there is Cort as well, who is now likely to spend the rest of his life in an insane asylum, if he is lucky.'

'Well, he must be packed off to England immediately,' she said breezily. 'As for the dreadful accident which claimed the life of poor Mr Macintyre . . .'