‘Diane, I’ve found Brian Mullen.’

‘Thank God. Is the child all right?’

‘No, listen. I said I’ve found Mullen. He’s unconscious – he looks as though he’s taken a bad blow to the head, and there’s quite a bit of blood. But he’s breathing all right. I’ve got an ambulance on its way.’

‘And Luanne?’

Cooper didn’t answer for a moment. He was staring at the long rows of looms, the gleaming wooden bobbins. White walls and dusty shelves, the flash of his Maglite reflected and multiplied like stars in the glass roof of the weaving shed. And, almost too far away, a distant doorway that must lead out of the mill to the goyt, where the deep channels drew water from the river.

‘Ben, are you there? What about the child?’

‘There’s no sign of her, Diane. She’s gone.’

There was silence on the other end of the phone for a moment. Silence, apart from the distant sound of a car engine and faint, echoing voices. He pictured Fry still in the parking levels, struggling to cope with members of the public wanting to remove their cars.

‘OK, Ben, hang on there. Stay with Mullen until assistance comes. Is Georgi with you?’

‘I think he’s still upstairs. But, Diane –’

‘Just don’t do anything stupid.’

And then she was gone. Cooper sighed as he ended the call, and checked Brian Mullen’s pulse and breathing again. His skin felt very cold, so Cooper covered him with a bolt of cloth. There wasn’t much he could do to stop the bleeding, but scalp wounds always looked worse than they really were.

He knew he ought to wait with Mullen, just as Diane said. But he was too conscious of time ticking away, too painfully aware that he might have been able to save John Lowther’s life yesterday, if he’d acted more quickly. How could he sit here now and wait while a small girl was nearby, needing his help? Luanne Mullen might at this moment be at risk in the darkness. The thought was intolerable. He knew he’d never be able to live with himself if he did nothing.

Goading himself into action, Cooper ran back to the stairs to shout for Georgi Kotsev, at the expense of destroying the silence in the mill. He was saved the trouble when Kotsev appeared at the top of the wooden steps, looking huge framed in Cooper’s torchlight.

‘A problem, Ben?’

‘Come down, Georgi, will you?’

Kotsev cursed quietly when he saw the body. ‘And the child?’

‘She’s not here.’

‘Dyavol da go vzeme.’

‘Stay with him, will you, Georgi? Help is on the way.’

‘Where are you going?’

‘To find the child.’

They looked at each other for a moment. Kotsev seemed about to say something, but changed his mind. He nodded briefly.

‘I understand.’

Then Cooper left him with Brian Mullen, and hurried down to the far end of the shed, tracking the sound of a closing door somewhere ahead. Noises echoed so much inside the mill that it was impossible to move around quietly. But it wasn’t quite so easy to tell what direction the noise came from.

He had no idea of the layout at this end of the mill. Above Cooper’s head, a bridge crossed over the looms to the mill entrance at road level. Ahead of him, a cavernous space gradually revealed itself to be the boiler house. Four black, riveted monsters glinted in his torch beam. Strangely, their upper surfaces were being used to store rabbit hutches.

He climbed back up the steps to a heavy steel door set into the outer wall. It looked like the entrance to a tunnel that would lead to the base of the mill chimney. He supposed someone must once have had to crawl in there to clean out the flue. Cooper paused for a moment, trying to decide between several doors and a series of smaller rooms, cramped spaces after the length of the weaving shed.

The door he chose turned out to be the bobbin room. The floorboards squealed and moved under the pressure of his feet as he entered. It occurred to him that he could be the ghost of Arkwright himself, prowling the mill at night, tracking down a fugitive child apprentice.

One flick of his torch showed Cooper a room like nothing he’d ever seen before. It contained dozens of musty-smelling hessian sacks spilling bobbins on to the floor. There were wooden tubs full of bobbins, bobbins in drawers and hanging on the walls. And above his head there were hundreds more of them strung in bunches – a thick layer of bobbins hanging as if they’d grown from the ceiling, like a strange fungal growth or a thousand stalactites filling every available inch. There were all kinds of shapes, sizes and colours, and they rattled slightly in a breeze blowing from an open door. Cooper could feel the chill striking through the doorway, and knew this must be the passage that led outside to the goyt, and to the river.

He slipped through the door on to a wooden walkway over the water channel. This area was open to the air, filled with the noise of the river and the sensation of empty space all around and above him in the darkness. The water that had once driven the mill’s waterwheels still ran the turbines, and it flowed fast under the walkway here. He could hear its rush and feel the vibrations of the current.

But beyond the end rail was a stagnant basin. His torch picked out iron chains hanging from ancient pulleys, coated with dust and cobwebs. The chains disappeared into the murk, reaching down towards mysterious shapes that he barely glimpsed in the depths, metal structures with a forgotten purpose. Cooper shivered as he saw bits of dead vegetation floating on the surface. Even an adult might have difficulty in that water. Imagine getting tangled in the chains and dragged to the bottom.

His torchlight illuminated a warning sign. But was it the fast-flowing goyt it was warning of? Or the still, dark basin with its shadows below the surface?

Cooper turned sharply to the left, not sure what he was reacting to. His senses were confused by the adjustment from the silent interior of the mill to the noise outside. A series of explosions reminded him that the fireworks display was still going on over the village. The cascade of coloured light helped him to orientate himself. Beyond the goyt he could make out the bank of the river, and directly in front of him was an area of slippery concrete channels and sudden drops into black, lethal water.

It didn’t feel any safer out here than it had inside. Of course, he ought to let Fry know where he was. So Cooper tried his phone again. But he was down by the river now, with the vast bulk of the mill behind him and the limestone crags towering on both sides. He raised his phone to head height and moved it in a different direction. No signal.

The roar of the weir sounded much louder at night. Now that he was close to it, it almost drowned the crack and scream of the fireworks launching from High Tor. Cooper strained to listen for sounds of movement above the rush of water from the weir and the hum of the turbines in the mill. The only other noise he could hear was a tap-tap-tap against the side of the channel as a polystyrene cup bobbed on the surface of the water. Tap-tap-tap on the concrete walls.

He thought he heard a shout somewhere, a woman’s voice. But the words were incomprehensible. He was almost sure he saw a shadow flickering, and caught the rustle of a long skirt on concrete.

Then the tap-tap-tap became a clatter, the sudden sound of running footsteps. Cooper swung his torch, but he couldn’t tell which direction the footsteps were coming from. The flashes and crashing of the fireworks were too disorientating, the reflection of his Maglite off the dark water too confusing.

So he spun round too late and didn’t see the black shape that came at him out of the night, or the fists that smashed into him and knocked him off balance. He teetered for a moment on the concrete edge, drawing a breath to cry out. His torch dropped from his hand and plunged into the goyt with a loud splash. A second later, Cooper was following it. He plunged into the water, falling towards the light as it swirled and spun towards the muddy depths.