Distant voices were shouting.

‘RUN!’

‘GET CLEAR!’

Gunson ran, flailing alongside Swinden for the hillside where Fountain and Craven and the other men were waiting, arms outstretched, to pull them to safety.

It was too late.

He couldn’t find purchase in the dirt crumbling down the collapsing bank. He slid and cried out, pushing at the trembling flank of the embankment to regain his balance. Black cracks appeared, abysses to suck him down. He was moving too slowly to escape an unseen monster gaining on him, those childhood nightmares now a reality. He looked up to see Swinden being yanked clear of the embankment. Another shudder and the earth beneath his feet disappeared. He was falling, pedalling his feet into a bottomless void. Then there were hands gripping him, and he was landing heavily on solid ground, face down, choking on dirt. He rolled onto his back, gasping for air.

Craven was bending over him, panting heavily. Gunson reached up and Craven grasped his hand, pulling him to his feet. He cringed as a bellowing roar echoed round the valley. Craven was shouting but he couldn’t make out the words. It didn’t matter. Nothing mattered. He was witnessing the collapse of his embankment, the entire middle section dissolving in an ear-shattering cascade of rocks and froth.

He tried to speak, but no sound came and this was terrifying in itself. Craven was screaming at him, tugging at his coat. ‘Move, man!’

He blindly followed him up the hillside, scrabbling in the dirt.

Fountain was there, swinging a lantern to attract their attention. His eyes were bulging. ‘We have to send a warning down!’

‘How far?’ said Craven. He took hold of Gunson’s collar and shook him. ‘How far will it go? Damflask? The Stacey Wheel? We have to send men down now!’

Gunson found his voice at last. ‘No horse can outrun that,’ he whispered.

The monstrous cascade was already past them, the river a snake shedding its skin, discarding the boulders in its bed and the trees on its banks, carving itself a new shape as it raced down the valley.

He cowered as another blast echoed off the hills.

Fountain laughed wildly and Gunson looked at him, aghast.

‘The dynamite,’ Fountain said. ‘It finally went off.’

Craven shook Gunson’s arm. ‘How far? How far?’

Craven’s face was a mask of terror. His men had built that dam, to the specifications Gunson had provided.

He batted Craven away and spoke as calmly as he could, but his voice shook with every beat of his heart. ‘The banks might break even as far as Little Matlock but it should subside before it gets to Malin Bridge.’ He took a deep breath, afraid suddenly that he would vomit in front of these men. The moment passed. ‘If it reaches Hillfoot unabated and joins with the Don… then I don’t know. I’m sorry, I don’t know. We’re in God’s hands now.’

Fountain dropped to his knees. ‘Then God help us,’ he said.