Falco takes a long swig of benzene. ‘G’hals,’ she says. ‘Saddle up.’

* * *

Beams of light streak my face, grit-laden air buffets through the thin gap that serves as a window in the side of the carriage. A prime spot this, away from the stink of the passenger cars. So far no one has dared asked me to move, cringing away from my bandaged face. Even the soldiers did not want to look too closely at me while boarding, not after I started to cough on them; they let me pass with a disgusted flick of the hand.

I take a scrappy piece of paper from my pocket and peer out of the window. A squat weather-eaten boulder is sliding past. Toad rock, Falco has scrawled on the hand-drawn map. Just past it, hatched in ink, is what I’m looking for. Shade’s Gulch. According to Falco it’s a long, narrow canyon, deep and shadowed enough to hide any activity from the satellites that might be tracking the Air Line from above.

My shoulder gives a sullen throb. I reach into the Marshal’s coat for the small canister of oxygen Falco was able to score in Drax, and fill my lungs with a few deep breaths. I follow it up with two beads at once. I’m in a bad way, my shoulder burning and head aching, my whole body battered and sore.

It will have to be enough. As the rock slides out of view, I reach for the pistol hidden in my pocket. This is it. I close my eyes, knowing that somewhere, beyond the terraform, in the cells of my blood, they are waiting. I step forwards and shove open the wagon door.

Desert air blasts my face, sending the bandages flapping.

‘Hey,’ the shotgunner yells as I step out. ‘You can’t—’

I grasp his padded armour and spin, throwing him from the train. He’s whisked away with a shriek, the shotgun clattering from his grip. The wound in my shoulder tugs as I seize the gun and arm it.

A second later the Air Line plunges into cold, ochre shadow. We’re in the canyon.

Ahead of me, a guard carriage rattles and sways and after it, last of all, comes the Iron Slug.

The noise of the train echoes against the canyon walls, rebounding so that the world seems full of beating wings. But beneath that noise is another sound, a many-throated growl that grows louder until, with a roar, two G’hal mares burst over the ridge of the canyon, skidding down a steep path to race behind the train. The riders scream a battle cry.