Was it the mouthless creature that had made that sound? The truth was, it could be anything. But as the children lived a mind-rotting existence of boredom mixed with fear, their imaginations were working hard and fast.

There were no more clues. The thud was followed by a long period of quiet.

Sam and Rhiannon sat there in the darkness. Unmoving. For a brief moment they had been back at home, with their families, snuggled up on the sofa on a Saturday night.

Now they were back in this cold comfortless carriage.

They could hear the twins sleeping, their breathing shallow and feeble. Sam felt something touch his knee. He realized it was Rhiannon’s fingers. She was reaching out for him. He took hold of her hand and squeezed. She was trembling. After a long while, which seemed like hours, there was another thud, nearer this time. Once again it was followed by nothing but deep silence.

Sam could stand it no longer. He went over to the window. Looked out at the platform. There was nothing moving out there. The sound hadn’t come from the direction of Nick and Rachel’s sleeping carriage, and he hadn’t heard or seen anything of them, but it was possible that they could have gone down to one of the other carriages without being noticed.

At last there came another bang, closer still but muffled again. Then a light appeared at the window in the door leading to the next carriage. A small flickering flame. Sam screwed up his eyes, straining to see what it was. He couldn’t go any closer as his chain prevented him from moving far.

Now a sheet of cardboard appeared at the window. It had been ripped from a computer box and there was writing on it. Seven words scrawled in marker pen. Whoever was there adjusted the cardboard so that the flame lit it from the side.

Sam read:

kip qwite I am her to help

It took him a few seconds to realize that it was meant to say ‘Keep quiet I am here to help’. And no sooner had he worked it out than the cardboard disappeared and was replaced by a face.

Sam jumped.

It was the same face he had seen at the window.

Only it was different.

He smiled.

What an idiot he was.

When he had seen the face before it had been upside down. Hanging from the roof of the carriage.

The bald crown had been its chin. Sam had been looking for a mouth where the forehead was.

Now that it was the right way up he could see that it was a boy’s face. Black with dirt, eyes wide, small sharp teeth very white. There was a shock of dark, tangled hair sprouting from the top. The hair that Sam had thought was a beard when he had first seen it upside down outside the carriage.

The face grinned and then its owner raised a fist and gave a thumbs up. The flame snapped off. A few seconds later there was a familiar dull thud and the sound of falling glass, tinkling on to the metal floor.

‘If you hear the butchers, yell.’ It was the quietest whisper in the world.

Then silence.

Sam counted the seconds in his head. It was all he could think of to fill the time and ease the tension that was growing inside him like a balloon inflating.

He got up to sixty-five before the flame flickered back on. Startlingly close. Sam jerked back in fright. The boy had climbed through the window and come down the carriage without them hearing or seeing anything. The flame was lit just long enough for them to get a proper look at him. He was about Sam’s size, skinny and wiry looking, wearing shorts, trainers and a woman’s leather jacket with the sleeves cut off halfway. He had a leather satchel slung over one shoulder and he was carrying a cigarette lighter and a blanket.

He flicked the lighter and the flame died.

‘Not safe,’ he whispered. ‘If the butchers see the light they’ll come running, mark my words.’

‘Who are you?’ said Sam.

‘Stay quiet,’ the boy hissed. ‘You’re getting out of here pronto.’

Sam felt the boy’s hands groping along his arms to the handcuffs.

‘Handy-cuffs,’ he breathed in Sam’s ear. ‘Soon have these bracelets off. No more than a jiffy.’

There was rattling and scraping as the boy poked around in the lock with some kind of tool. Then, finally, a snap and rattle and the cuffs came loose.

Sam now felt the boy slip the lighter into his hands.

‘Light me, skipper,’ he said. ‘The Kid needs to see his surroundings.’

Sam rolled the flint on the lighter and the flame jumped and sparked. The boy was already at the end of the carriage, holding the blanket across the whole width.

‘There’s sticky-tape on my utility bat-belt,’ he said, nodding downwards.

Sam saw a roll of strong black tape hanging from a piece of string at the boy’s waist. He gave the lighter to Rhiannon and in a minute had managed to roughly tape the blanket up. Now if Nick and Rachel happened to look along the length of the train from inside their carriage, the blanket would block some of the light.

The boy grinned at Sam.

‘Nice work,’ he said and pushed Sam against the blanket. ‘Press your ear against blankie. Tell me if you hear anything moving, anything speaking, squeaking or meandering, even a mouse’s fart, so to speak. Get it? Got it? Good.’

The kid scuttled over to Rhiannon and inspected her wrists. Instead of handcuffs she was secured with plastic bindings.

‘Naughty,’ he said. ‘I’m going to need to cut.’ His hand darted into his pocket and came out with a little folding knife with a wide blade. He pulled it open with his teeth and smiled at Sam.

‘This should do the trick, eh what, Jeeves?’ he said. ‘It’s a wicked little snickersnee. Not half.’

He took the lighter from Rhiannon, gave it back to Sam and set to work. The blade was razor sharp and it sliced through the plastic in no time flat. As soon as Rhiannon’s hands came apart he blew out the flame.

‘Lights out, boys and girls.’

He drew Rhiannon and Sam into a huddle.

‘We have to go careful and quiet as spies. Can’t risk too much light. It’s like this. If I’d tried to get on the train from the platter-form those beastly butchers would have spotted me, no sweat. So I’ve gone right to the end and I’ve bonked and bashed my way all the way down the carriages, cos Mr and Mrs Lovely have fixed all the doors and windows shut. So we go back and out that same way. Once we get to the end, we drop down on to the tracks and slither back along under-the-neath of the train to where we can get up on to the platter-form and thence to the stairway to heaven. It’s the best way. Safe as milk. You follow?’

‘I’m not sure I can walk,’ said Rhiannon.

‘You can walk. When they have to your legs will do as you say. Just speak to them firm.’

‘I can’t.’

‘No such word as can’t. No such word as babagoozle neither!’

Rhiannon laughed, trying to stifle the sound.

‘You talk funny,’ she said.

‘That’s just the way it is,’ said the boy. ‘Now let’s get these two snoozing muckers out of here. Match me, Sidney!’

Sam worked out what he meant and quickly lit the flame again.

The boy hopped over to the two sleeping twins, unlocked them and shook them awake. They were groggy and feeble, with no idea what was going on.

‘This is going to be tricky, captain,’ the boy whispered. ‘These ones are weak as kitties.’ He glanced up at Sam. ‘You strong enough to help carry ’em, squirt?’

‘I don’t know,’ said Sam. ‘I’ll try. I don’t feel too good myself.’

‘You don’t look it, skipper.’

Jason looked up at the boy, fear pulling at his face.

‘Who are you?’

‘I’m the Miracle Kid,’ said the boy. ‘The lizard boy, something of a worm and something of a cat. King of the tunnels. I’ll have you out of here in a thrice, I do declare.’

Jason opened his mouth wide to say something and The Kid put a finger to his lips and shushed him. He winked.