Craven gave a grudging nod.

‘Well then. Dynamite the top of the overspill and a goodly chunk of water will be immediately released, and that will relieve the pressure on the embankment. What do you say?’

‘Yes,’ said Fountain immediately.

The man’s sense of urgency was infecting Gunson, or so he told himself. His belly was hollow, although he’d eaten a good dinner – his animal self trying to override his logical brain with that most primal message: Beware.

‘David?’ he said.

Craven wiped rain from his face. ‘We’ve not long finished building the damned thing… All right, I’ll get some men on it.’ He marched away.

Over the next hour, as the rain eased and stars came out to prick the sky above the reservoir, two attempts were made to demolish the top of the weir. Twice, Gunson held his breath in anticipation of the explosion, and then released it, bewildered.

Craven appeared at his side. ‘It must have got wet, the dynamite.’

Fountain hurried over. ‘Come and see this.’

Again, Gunson negotiated the steep side of the embankment until the crack was at his feet. He toed it, gingerly. ‘It’s no wider.’

‘Wait,’ said Fountain.

Gunson breathed into his hands to warm his face and thought fleetingly about the fireside he had left. Nothing had changed and he opened his mouth to tell Fountain that this must surely now wait until the following day, when he saw the expression on the man’s face and followed his gaze to see water was dribbling between their feet and into the crack.

He looked up, dismayed. Water was running down the embankment’s face. The reservoir was overflowing. ‘But the embankment is solid,’ he muttered.

‘What did you say?’

‘The crack. It’s no wider.’

Gunson turned away.

‘Where are you going?’ said Fountain.

‘To check the pipes.’

George Swinden, the site foreman, stood outside the valve house.

‘There’s no imminent danger,’ Gunson said to Swinden, gesturing for him to follow him inside, eager for the shelter of the building. ‘I’d like to check the pressures again. Were it not such a wild night…’ he stopped when he realised the foreman had not followed him through the door.

‘George?’

A cry came from outside, tattered by the wind. It could have been the screech of an owl. Gunson paused, acutely aware of the glass rattling in the windowpane. A wild night, yes. Not a disastrous one.

Swinden darted into the valve house. ‘It’s going!’

‘What?’

‘The dam!’

The man was making no sense. Gunson stared at him. ‘No, it’s not. Get a grip, man.’

‘Come on, John!’

Swinden grabbed him by the arm, his grip fierce and desperation in his face. Gunson let Swinden pull him outside.

He looked up, knowing there would be nothing to see, that Swinden was having some sort of hysterical reaction. His stomach caved. The middle of the embankment was collapsing – crumbling – and still he could not believe that the entire dam wall could fail.

Swinden pushed him and he almost lost his footing. ‘What are you doing, man?’