Meanwhile, at the rear of the train, Constable Bluejohn, standing on his flatbed gently rocking with the motion, thundered a troll threat, reached out and plucked a miscreant from his foothold unwisely close to the track. When he was joined by Detritus, the assailants soon discovered that aiming boulders at the trolls was a fool’s errand. The lads, who were quite literally in their element, just grabbed them and tossed them back with interest.

Looking out of a broken window, Moist saw a small swarm of goblins leave the train and at first he thought, ha! Trust the buggers to run away, and then he mentally corrected himself: that was storybook thinking and with clearer eyesight and a bit of understanding he realized that the goblins were scrambling up to the delvers on the rocks and beating the shit out of them by diving into the multiple layers of dwarf clothing. The delvers discovered all too rapidly that trying to fight while a busy goblin was in your underwear was very bad for the concentration.

Of the Twilight the Darkness suddenly appeared at Moist’s elbow. He was wearing a helmet that was far too big for him and spun around on his head. He pushed one arm into the greasy nest he called a jacket and struck a pose.

‘Marvellous, ain’t they? Always going for the gonads.’

There were screams, sometimes high-pitched, as the delvers lost their hold and fell down either under the train or into the water, still fighting the speedy goblins.

As Iron Girder steadfastly steamed on round the next bend, she and her coal tender came into Moist’s field of vision and he was horrified to see that a couple of delvers had gained a foothold on the tender. They were being held at bay by a soot-blackened stoker who was valiantly protecting access to the footplate by wielding his shovel to deadly effect. Moist caught a glimpse between the chaos of fighting bodies of the stoker dispatching one of the delvers, kicking him over the side. A massive blow with the shovel dealt with the other dwarf, and the stoker dropped out of sight. His sheer efficiency had been vaguely disturbing. Perhaps that’s the legendary Stoker Blake, Moist thought, and then ducked back inside as another boulder crashed past.

Finally the bombardment ceased and Moist made his way down the train. He found the Low King in one of the armoured carriages with Bashfullsson and the rest of his party. There was blood on the King’s beard.

‘The foe is either fleeing or dead,’ the King said. ‘The wounded will be taken aboard under lock and key and undoubtedly the good commander will have them talking to him as if they were the best of friends. He has a knack for that sort of thing.’

A while later Moist went into the guard’s van, where Commander Vimes was having little chats to grags and their fellow travellers. He was speaking in his very low, understanding voice.