'You will!' As I spoke I grabbed his wrist and swung my foot against his shin, knocking his legs from under him. He writhed as he fell and succeeded in pulling me over too. The ice sheet dipped under our weight and we both slid towards the water. My grip on Iuda's wrist was now reciprocated by his on mine, but there was no grip that either of us could find on the glassy surface beneath us to halt our descent. A swathe of powdered ice sprayed into my face, sheared from the surface as Iuda dug in the teeth of his knife to slow our motion. He came to a halt on the very lip of the ice, but my impact into him knocked him a little further over, so that his legs dipped into the water.

Wriggling on my back, I kicked at the knife in his hand and it skated across the ice and over the edge, disappearing into the water with a plop. Iuda spread his hands and arms wide across the surface of the ice, trying to find purchase, trying to prevent himself from slipping into the cold, turbid water. But he was no voordalak, and did not have their ability to find a grip on the most polished of surfaces.

I regained my feet as he hung limply off the edge of the ice, now up to his chest in water and, with every movement he made, slipping in a little deeper.

'You can't let me die,' he said, not as a plea but as a statement of fact.

'Why not?'

'That way you'll never know.'

I stamped my foot firmly beside his hand. He grabbed it and clung to it, his arm wrapping around my leg like a serpent's tail.

'So,' I asked, breathing deeply and trying to calm myself now I had the upper hand, 'was it Margarita or Domnikiia you were with?'

He looked up at me with his head cocked slightly to one side. 'It was…' He paused in thought, as though he had been asked whether he would prefer beef or mutton for dinner. 'Margarita!' he announced with an air of decision. Then he yanked firmly on my leg, throwing me once again on to my back on the ice. As I began to slide once more towards the river, Iuda too had lost his only anchorage and his head disappeared beneath the surface.

The ice sheet beneath me began to tip and I found myself sliding even faster towards the water into which Iuda had just disappeared. I rolled on to my stomach and splayed my arms out wide, but just like Iuda, I could find little purchase. My right hand found a momentary grip, but the fingers of my left could do nothing. Within seconds I splashed into the water, going under and feeling a new coldness that infiltrated those last few parts of me that had been protected by my clothing. By the time I bobbed back to the surface, so had he.

'I can't lie to you any more, Lyosha,' he said, spitting out some of the water that had filled his mouth and swallowing the rest. 'It was Dominique.'

Once again he disappeared beneath the waves. I might have dived down to pull him back to the surface, but my concern now was more that the current was hurtling me towards the pillars of the bridge itself. I put my arms and legs out in front of me, but even then I could not protect myself entirely from the force of the impact. The wind was knocked out of me as my chest collided with the wooden support and my head bashed against it, almost knocking me out. Only some instinct told me to hold on to whatever I could grab, otherwise, weighed down by my wet clothes, I would have sunk straight to the riverbed.

Moments later, I was again fully conscious. I hauled myself up out of the water and entwined my legs around one of the beams. Looking to my left, I saw Iuda also climbing out of the water on to the substructure of the bridge. His motion was like that of a newt, dragging itself from the slime of its watery habitat on to dry land. He paused for a moment, panting, and only then looked around to see me advancing on him, stretching from pillar to beam across the wooden web that comprised the bridge's foundations.

Iuda ducked inside, crossing underneath the bridge. I followed, but made better ground, managing to get both to the other side of the bridge and closer to him. We were now dead centre in the river, about as far from one bank as from the other. Above our heads, hundreds of French were trampling one another in an attempt to get over to the right bank. Russian cannonballs splashed into the river around us. Stretching away from us to the south, the river flowed fast and free. Beyond this bridge, past what little the current had left of the shattered other bridge, there was nothing for miles. Somewhere, way downstream, there would be some other bridge against which all those dead who fell here would eventually congregate. If not, the Black Sea awaited them, far, far away.

Iuda leapt out into the water and I made a grab after him. With my left hand I just managed to get a hold of a clump of his filthy blond hair, whilst keeping myself anchored to the bridge with my right. With only two fingers and a thumb, it was hard to get a good grip, but his hair was long and soon I had it entwined. He was at my mercy, up to his neck in the water. I could duck him beneath it, pull him to safety, or let him go.

'Tell me the truth!' I screamed at him.

'I have told you the truth,' he replied, laughing despite his predicament.

'When?' I demanded. It was not a rhetorical question and he knew it. What I wanted to know was which of his two contradictory statements was true.

'Often,' was his only reply, again accompanied by a laugh.

I pushed him downwards under the water, counting the seconds to myself to be sure that he would not die. I pulled him back up and he gasped for breath, but never lost his smile.

'Tell me!' I screamed at him again.

'You can't torture me, Lyosha.' He raised his hand to clear the wet hair from his eyes. 'I have the ultimate protection that you'll never believe me. I've told you everything – not just everything that's true, but everything else as well. All I can offer you is the ultimate enlightenment; not just what is but what could be. To know everything is to know nothing. What's the point in asking any more? What's the point in forcing it out of me? You might as well torture a coin and expect it to turn up tails.'

I pushed his head back under the water. He was right. Many people choose to live by their reputation; Iuda chose to live by the lack of it. With my help, he had put himself in a situation where I could lend no credence to anything he said. However many times I dipped his head beneath the waves, he could change his answer. The final answer would never be the definitive one, because another different answer could always follow. I could put Iuda through the agonies of hell and he could scream 'Margarita' nine hundred and ninety-nine times and I would still not believe him, for fear that on the thousandth he would mutter 'Domnikiia'.

I pulled him back up to the surface, tightening my grip on his hair as though to pull it out of his scalp.

'You're slow today, Lyosha,' he said. 'Do you still think you can get the truth out of me?'

Silistria had taught me more than one thing about torture. It had taught me about being a victim, but I had also learned about being a perpetrator. I'd learned that it's not always about gaining information; sometimes it's an end in itself.

I shook my head and waited for the look in his eyes that showed he realized that the torture was over. The instant I saw it, I pushed his head back under and began to count again. He knew that, this time, I was not intending to pull him back up again. He had chosen a game that led to his own destruction; chosen to lose with a clever move rather than survive through a mundane one. As I counted the seconds, he struggled to break free; past ten, past twenty, thirty and forty. Then he quietened. It was not long enough for a man to drown – I knew he was bluffing. My hand was so cold I could scarcely feel his head beneath it. I squeezed tighter, unable to feel even pain and wondering if I might be breaking my own fingers by gripping so tightly. After about a minute he began to struggle again and then a convulsion ripped through his body. Had that been his final, irresistible, instinctive attempt to breathe, when the urging of his lungs overcame the knowledge that he was surrounded not by air but by water? Afterwards, he moved no more.