A wave reached out to engulf Irene and Vale, sweeping them off the ice-smooth marble and holding them in its grasp. Those of the soldiers who could move scrambled for cover, abandoning their guns. Irene screamed as the waters boiled up around them and struggled to keep her head above the wave, her skirt a constricting mass around her legs.

‘Get ready!’ Kai’s voice rang in her ears, even through the tumbling water. ‘I’ll be able to control the beginning of the descent down the Campanile, but probably not the end, so hold your breath!’

The thought This is going to hurt stood out in the chaos. She emptied her lungs and then took in as much air as possible, trying to store as much oxygen as she could. She and Vale were several feet off the ground now, being dragged by the waters towards Kai’s water-spout. Hanging above the ground, she felt a new sense of awe. The immense waves Kai had raised were still dwarfed by the immensity of this prison, which was for much larger, much more powerful entities than them. Things that, even if they won free, could scarcely fit down a tiny staircase - she hoped.

The pseudo-tornado’s waters curved in a high arc over the iron bridge, to rest poised above the staircase where they had originally entered the prison. Then it fell down into the chasm, a twisting stream of liquid darkness that centred on the staircase, making the whole structure shudder and thrum as water hit iron. The sound was so loud that Irene raised her hands to cover her ears, trying to block it out. She could imagine the gush of water as it followed the spiral of the staircase. Jets would spout in all directions through the gaps in the panelling, but the main force of it would surge ever downwards. And as the dark shaft around the staircase narrowed and drew back to the dimensions of the Campanile below, there would be even less room for the water to escape. There would be nowhere for it to go, except down and out.

She hoped that anyone in the way had the sense to run.

Then Kai gestured towards her and Vale, and the waters pulled them towards him, like mere straws caught in an undercurrent. She took a last deep breath, her stomach knotting in pure terror, and then the rush of water swept all three of them giddily up through the air within the water-funnel. She was relieved, because if there was air, Kai was keeping them safe as he’d promised. They swung up and over the chasm in a single smooth arc, like an arrow’s flight, and then they plunged down into the stairwell.

At first the momentum was surprisingly smooth. She curled up instinctively, folding her arms over her head and tucking herself into a ball. The light was gone within moments, as the water swept the three of them round the first couple of curves in the stairs. It wasn’t as nauseating as it might have been. It felt more like the guided sliding of a helter-skelter than anything else, and Kai clearly had it under control. She clung to that thought like a talisman. She was going down an extremely high staircase underwater at high speed in the darkness. But she could trust Kai. He has it under control, she repeated to herself.

Then abruptly it was colder, and the water was no longer cradling her, but simply carrying her along like a fragment of straw. We’ve crossed the boundary into Venice, she thought grimly as she held on to the last of her air. Kai can’t function here, so we’ll just have to get through the rest of it.

The water now thumped her into the outer side of the staircase, banging her downwards like flotsam, spinning her round faster and faster. She hit the staircase again, the panelling, the stairs below her and the bottom of the stairs above her. Most of the blows were to her hips or shoulders, and she kept her head tucked in tightly, her breath burning in her lungs. There was no room for thought, just sheer panic as she crashed downwards in the darkness.

Abruptly it spat her out. The gush of water threw her out through the Campanile’s elegant portico and open gates and into the square beyond. Irene tumbled across the paving for several yards before she came to a halt. She lay there in the draining water, still curled up, the parts of her body that had banged into the staircase aching. Cold water washed past her cheek as she gasped for air. Her head was still spinning and she vomited, throwing up the little in her stomach onto the freshly washed stones.

‘Winters!’ Vale was shouting at her, his voice penetrating the general uproar. ‘Over here!’

She looked around, disorientated. It was full night. Lanterns flashed as they swung madly in the wind, and the square was a churning mess. Like her, others were sprawled in the water as the last of it flowed out across the Piazza. It drained into the shops and public buildings that bordered it, or ran over the paving and into the sea beyond. Uniformed guards around the Campanile’s entrance were also struggling to their feet. The size of the crowd suggested a near-mob - or would have, before one added an almighty flood in the near-darkness. It was definitely a mob now. The dim municipal lighting, combined with the masks most people were wearing, turned the scene into a nightmare.

Kai was lying on his face, groaning. Vale, looking battered but mobile, had one of Kai’s arms over his shoulders and was trying to haul him to his feet. It said something about Vale’s own condition that he hadn’t managed it yet. His arm was bleeding again. Irene pulled on her own mask as she staggered across to join them, her joints protesting with every step, and wedged her shoulder under Kai’s other arm. ‘Get - get to the Train,’ she coughed, tasting bile with every word.

‘You need not belabour the obvious, Winters,’ Vale snapped.

‘Get them!’ Lord Guantes shouted from somewhere in the darkness, his voice furious beyond any semblance of control.