The door at the end of the passage led into darkness. Not the kind of darkness where you could just about see your way, but total pitch-darkness of the sort that suggested underground abysses or hidden cellars. She didn’t think a demand to turn the lights on would be much help.

With an inward sigh, Irene stepped through.

She was abruptly in the Train’s engine car, which was dark too, but she could now see a little further. It was filled with complex dials and levers, a coal-powered boiler to supply steam and a lot of gleaming oily pistons. She looked around for any obvious clues to take things forward.

There. A heavy silver padlock and chain were fastened around one of the largest levers, holding it in an upright position. It looked more ornamental than functional, something that anyone could easily lift off the handle and remove. But, she reminded herself, the symbolism might be important here. The memory of another chain months ago, and the trap that had been woven into it, made her hesitate. That time she’d been infected with raw chaos, and she’d only survived because Kai had broken her free. He wasn’t here now.

The machinery hummed around her. Then another scream was ripped from the steam whistle, as if - no, she was sure of it - the Train was impatient with the delay. But how was she supposed to protect herself in a high-chaos environment, when anything she might do could infect her with the stuff?

Well, perhaps she might try protecting herself in advance this time …

She scooped up a fingerful of oily grease and hastily scribbled her own name in the Language on the palm of her left hand, then repeated the process on the right. Hopefully defining herself in this way would help keep the chaos out. It had better: she was out of ideas.

‘And the princess saw the horse’s bridle and reins,’ she pronounced, flexing her fingers. The words hummed in her mouth and echoed in the engine car as she spoke them. ‘And she said to the horse, “Now I shall free you from your captivity, and you in turn will help me and those with me to escape.”’

The hum around her rose, throbbing loud enough to hurt her ears. ‘And the princess took the bridle and reins …’ She was having to shout now to hear herself over the sound of the engine. The Language tore at her throat and weighed on her lungs. Her body was moving as she spoke, and she could not, even for the sake of her sanity, be sure if she was moving of her own volition or because the Language was forcing the movements from her.

Her hands closed on the chain, and the bracelets that Silver had given her shattered, flying into fragments and cascading to the floor in a scatter of links. The mask covering her face dissolved, crumbling into dust that clung to her wet skin. She could feel her own name in the Language burning into her skin, but the metal of the chain itself was cold and as normal as anything here could be. ‘And she drew it from the horse’s neck …’ Her arms rose upwards, dragging the chain from where it hung over the metal handle like a noose. For a long moment it seemed to cling to the top of the lever, dragging against it as if unwilling to be released.

She set her teeth. ‘And it came free!’ she shouted.

The small metal ting of the chain coming loose rang through the cabin, even louder than the pulsing of the engines. The metal links were slick against her palms now, like oil made solid. They snaked around her hands, curling about her wrists almost affectionately.

The Train shuddered lengthwise, the movement jerking along the carriage like the crack of a whip. Irene lost her balance, falling to her knees. And as if it had been waiting for its moment, the chain lunged for her neck. She cried out in shock, holding her now tightly bound hands as far away from her as she could, clinging desperately to the chain to stop it getting any closer. The chain’s ends brushed coldly against her skin, trying to get nearer to her throat.

Suddenly it slipped between her fingers, freeing her wrists, but flinging itself around her neck. She managed to get her fingers between the chain and her skin, but it tightened against them, cutting into her flesh in a vicious, deliberate attempt at murder. Her pulse rang in her ears even louder than the screaming of the Train’s whistle.

She shut her eyes, forcing back panic, holding on to a last thread of consciousness. There was still air in her lungs. ‘Chain, slacken,’ she wheezed, the words coming out in a barely audible whisper. ‘Slacken enough for me to breathe.’

The chain relaxed its stranglehold, and the flashing lights in front of her eyes receded. It shifted and flexed against her fingers, writhing around her neck as if trying to find a new avenue for attack. If it was somehow alive, then the Language wouldn’t have a lasting effect on it. She could throw it out of the window, perhaps? Or, better still, destroy it? Tell it to come to pieces? But what if it re-joined itself?

The boiler door drew her eye, and she staggered across to it and threw the door open. Heat came rushing out, searing her face and making her choke again. The chain tightened as if in response, grinding the fingers of her other hand against her neck and dragging her head back.

‘Fae silver chain,’ she gritted out, being as precise as she could, ‘loosen! Be quiescent! HOLD STILL!’

The chain went slack enough for her to wrench it over her head and get a firm hold of it with both hands. She balled it up and flung it into the furnace, and it clattered and twisted as it left her hands, trying to move and lunge at her. She slammed the boiler door on it, her hands aching from the scorching heat. It hammered at the door, but after a few seconds its last desperate clangs died away.

Then the great lever came down of its own volition.