Today, however, Boulder City’s buses were transporting not only their regular dinosaur customers but also an additional cohort of unauthorised passengers. Ant-soldier stowaways! Swarms of these undercover operatives had scuttled aboard during the night. The Number 1 bus, which served the main artery through the city, carried the largest contingent – an entire division, comprising more than 10,000 ants. They were concealed in various inconspicuous locations: under the doorsills, inside the toolbox, clinging to the undercarriage, camouflaged inside the coal bunker. On such a huge vehicle, hiding a division of the Imperial Formican Army was easy.

Ten minutes after the Number 1 bus drove onto the hectic, thunderous street, it pulled in at its first stop. Hard on the heels of several dinosaur commuters, a company of 200 ant soldiers detached themselves from beneath the doorsill and dropped to the ground. Each one held a mine-grain in its mouth. They immediately filed into a crack in the pavement, their tiny black bodies invisible against the wet surface, and began zigzagging towards their destination. The dinosaurs stomping along the steamy street were oblivious to their presence. The ants, on the other hand, were all too aware of the dinosaurs. Every time a hulking great Tyrannosaurus passed above them, their world went black; there was also the ever-present danger of being crushed to death should they poke their heads out of the cracks. No catastrophes befell them, however, and eventually they arrived at a building. It was so vast that its front door opened into the clouds, and the upper storeys were lost in the ether. The ant troops stole through the gap beneath the door and filed in.

All dinosaur architecture was high-rise. From the ants’ perspective, each building was effectively its own world; for them, being indoors was no different from standing outside in an open field. This particular structure was a warehouse – a gloomy world whose only sun was a small, high-set window that let in just a little light. The ants wove their way across its wide floor, between piles of goods, until they reached a row of tall wooden casks. These contained kerosene that the dinosaurs used for lighting. Since the dinosaur world had not yet entered the Electric Age, they relied on oil lamps at night. Searching carefully, the soldier ants found several patches of moisture on the floor where the casks had leaked slightly. They removed the mine-grains from their mouths and stuck them to these oily patches. Soon, more than a hundred mine-grains had been put in place. The soldiers aimed their posteriors at the mines, and, at the first lieutenant’s command, sprayed a droplet of formic acid on each one. The acid began to slowly eat through the shell of each mine-grain, activating the ignition fuse. The delay had been set for six hours, scheduling ignition for two o’clock that afternoon.