‘If you please, ah grag nun^[72], we have lost track of two agents on one of the trains,’ said the acolyte. ‘Alas, we are no longer in touch with them.’

The grag commander looked up. ‘Ah-ha!’ he said. ‘Where were they when we last heard from them?’

‘On the regular service from Sto Lat to Zemphis. But they failed to report at Big Cabbage or earlier as the train passed through Cranbury.’

‘Are you certain?’

The acolyte jumped. ‘Well, my lord, we are in the dark, but I think so …’

‘In that case,’ said the grag, ‘make it known that we are no longer bothering with the other routes. Our … package must have been on that train to Zemphis. And from there … The Paps await, and they take no prisoners! They, my friend, are coming to us. And the creatures that live in the Paps will be our allies! It’s all about the railway now, and we know that it is in the compass of our agents to stop those blasted wheels turning. Be mindful of bridges, however. The enemy favours the dreadful stone people who love to guard them. And surely tunnels can also be made to fail … This wretched technology contains the seeds of fallibility.’

‘Yes, grag nun, we know that the locomotive has to stop frequently for coal and water. Deprive it of either and there is no locomotive, just a lump of old iron. So, the coal bunkers and, yes, water cranes … There will be guards, of course, but they should be easy to overcome when stationary.’

The chief grag returned to his study of the words of Tak as annotated by Grag Hamcrusher.

‘Let me know when the deed is done.’

Down at the Zemphis terminus, Iron Girder looked even more spectacular up close. Dick Simnel was dressed smartly and grinning proudly as he showed off the glittering engine and all the dials and gauges on the footplate. Seeing Dick wearing clothes that had no grease on them was astonishing, like seeing a lion without a mane.

Along with Cheery Littlebottom and other members of the City Watch who had been summoned by Commander Vimes, Moist was surprised to see the cheerful and homely face of Constable Bluejohn, the largest troll on the force. Bluejohn, whom even Detritus described as ‘a big boy’, was by nature as gentle as a breeze and wouldn’t hurt a fly – at least not on purpose, although he could quite possibly tear a lion in half with his bare hands if needed. Nevertheless the sight of him on the scene of any fracas was an invitation to run a marathon in the other direction rather than face the megalith. He lived in a reinforced house somewhere in Sunink, a little town inadvisably nestling in the outskirts of Ankh-Morpork. They said that the sound of Bluejohn walking to work was better than an alarm clock.

Vimes marched off down the platform to greet the new arrivals. Cheery was looking very cheerful, as cheerful as any decoy could be who had been the winner of a battle and had come out more or less unscathed, except for a small scar which you had to have, didn’t you, or no one would believe you.