Matil met his gaze, held it for a moment, then spun away, calling in urgent Serican. Horns blared from the city walls, signal flags snapped high on their runners.

The confessors crashed against the crossbowmen as the lancers crashed against the confessors. In the midst of it all, the second engine fired. Chel saw the jerk, the twitch of the wheeled edifice, then something like a swarm rose into the air from behind it. It spread as it arced, wide and thin, dispersing like a dissipating flock, countless dark, round objects, almost too small to discern.

Tarfel recognized them. ‘Oh, no,’ he said. ‘Oh, no.’

The spreading cluster passed its apex and began to drop toward the men and horses around the engine. ‘What is it?’ Matil said, watching the objects fall. ‘What are they?’

The prince was ghost-pale, thick beads of sweat on the fuzz of his upper lip.

‘Demon eggs.’

They fell like stones, pelting the combatants and their surroundings, clattering from helmets, pinging against the engine’s great iron prow. Men cried and yelped when struck, and horses shied, and for a moment Chel was baffled, thinking that this fearsome weapon was little more than a giant sling. Then he saw the first jets of angry smoke from the fallen objects, heard that same alchemical hiss, and was at once afraid.

Small pops and flashes lit the melee, bursts of acrid smoke, cries and sprays of vivid blood. They grew in number and frequency, pattering like distant lightning in the dim centre of the combat as horses screamed and men wheeled in panic. Formations broke as confessors and house guards alike tried to flee the sudden fiery bursts that surrounded them.

‘Vedren, the engine!’

The horn blasts from the wall urging retreat were lost in the sounds of chaos and panic, the near side of the plateau already drenched with thick and choking smoke. Only those closest to the engine saw the lick of flame along its underside, heard the popping and hissing that issued from within. By then it was far, far too late.

A massive explosion ripped the engine in half, a blast of two parts, a heartbeat of force. The iron shield twitched as the engine’s body dissolved in a wall of flame, then it detonated, a miniature blinding white sun, summoned from nowhere, expanding over the plateau until Chel could see nothing but its fierce light through his eyelids. A booming crash squeezed them open again, in time to see the great black ploughshare wheeling through the air, one bounce on the bridge in its wake. It smashed down again, shearing against the bridge’s hard stone, one half skittering over the arc and smashing through the rail, the other pinwheeling along the structure’s length, a murderous whirl, shedding broken shards of black metal as it flew. At last, it crashed against the rail and fell back, jagged and inert, behind it a trail of cracked stone and dark iron daggers.