The Emperor asked Pasquin if he could return the river to its original course. But Pasquin couldn’t, and had to admit he was beaten.

Frost’s husband died the same night. She won her place in the Circle but all she would say was that she had failed to save him. She became locked in mourning and refused herself any pleasure.

The changes in people’s characters cannot be divorced from the changes in their bodies. An adolescent is passionate and changeable because of his changing body, not just his lack of experience. An octogenarian is fatalistic since he can feel his body failing, and knows it prefigures his death, not solely because he has seen friends die. Middle-aged mortals change more slowly than the very young and very old, so their characters are more stable. And we Eszai never age at all, so aspects of our characters are also fixed.

Moreover, I doubt any Eszai really grows up while the Emperor San is our immortal father. They preserve their identities against the grind of long centuries, and by their quirks they distance themselves from the crowds. So, Frost still retains the attitude of mourning. She lives for her work but complains she can’t achieve as much working alone. She leaves the fruits of genius scattered through the Fourlands, like the tidal mills of Marenna Dock, the Anga Shore breakwater on the Brandoch coast, and a hundred six-sailed wind pumps along Miredike and Atterdike that drain the malaria swamp.

Frost is, without doubt, a genius. The traits of genius often coincide with madness, but that isn’t strange, because if genius is an infinite capacity for taking pains, then you tell me what madness is.

I flew out of the dawn, into the Castle, my heart racing. I soared in over the curtain wall, bleeding off my downwind speed, and all the Castle’s quadrangles opened up as I passed over. Hidden inside and between its buildings, they revealed themselves to me.

I ignored the confusing levels of the roofs slipping away under me; the shallow lead cones of the six Dace Gate towers ascending in size from the bastions in the moat to the enormous barbican. I focused on the spire of the Throne Room as I glided over the Berm Lawns. The spire filled my vision-I flared my wings, swept up close to its wall and landed on a gargoyle projecting from halfway up.

The wind gusted; I steadied myself against the stone, turned around on my narrow perch and braced myself with one foot either side of the drainage channel. It was blocked with moss, pigeon shit and the grit weathered out of the stone. I kicked it clear with my toe and the black water spattered down onto the Throne Room’s sheet lead roof. I looked out down its length towards the North Façade; pinnacles and the tops of flying buttresses emerged at intervals around its edges.

Every gargoyle was different, arcing out to my left and right in a ring around the spire, with bulbous human faces and lolling tongues. The one I was standing on had a round, white pigeon’s egg in a nest of twigs amassed in the joint of its wing swept back to the wall. I always felt as if their flamboyant features had been carved for me. It seems too much effort to craft such inventive expressions, when the only people who will ever see them are me and the steeplejacks. Still, if a stone mason with carte blanche can’t have fun, who can?

I shook out my wings, hopped off the gargoyle and spiralled steeply down to the Berm Lawns.

The door at the end of the Simurgh Wing was locked. Typical. I can’t be expected to carry keys to all of the damn doors. I hammered on it but no one was within corridors’ distance.

I sprinted around the side of the building, on the grass between it and the Harcourt Barracks, past the armoury, the hospital and its herb garden. I sped onto the avenue bordered with tall poplars and ran down it, automatically avoiding the few uneven flagstones. The magnificent fronts of the Breckan and Simurgh Wings grew before me, with cool, modern open arches. I hastened through the space between them, taking the formal entrance through the Starglass Quadrangle.

I rushed past astronomical and horological instruments, on the main path between their large, square enclosures. The dew made the flint cobbles set in concrete at the edge of the path as shiny and slippery as ice.

The gleaming Starglass Clock struck ten as I passed. I counted its chimes almost subconsciously. The last one remained hovering in the air and seemed to grow louder, with a note of defiance, before fading.

Kings and governors and their retinues sometimes process along this route to the Throne Room when seeking the Emperor’s counsel. I hurtled through the massive portal. Its deeply carved tympanum panel showed San entering the Castle to stay for all perpetuity. I crossed into the narrow passage around the Throne Room.

Two guards with halberds stood always by its entrance. They took one look at me, unshaven and panting manically, ‘The Messenger!’

‘The Messenger!’

‘Let me through!’ I cried.

They pushed the doors wide across their polished arcs of stone.

The Emperor was sitting in the sunburst throne, and all was quiet behind the screen. He has resided in the Castle, seeing no more of the outside world than is visible from the walls, for fifteen hundred years.

I paused for breath, insignificant in size beside the column of the first arch. I leant forward, hands on knees, to catch my breath, and I was still trying to formulate what to say.

Diagonal shafts of sunlight so bright they looked solid, shone down from the east wall’s Gothic windows, high above the arcade of arches and the balcony where ten Imperial Fyrd bowmen stood in silence. Motes of dust and old incense in the air enjoyed brief fame, transformed to flecks of gold as they floated through the beams.

Without looking up or giving any indication that he had noticed my presence, the Emperor said, ‘Come here, Comet.’

I shuddered. I strode down the scarlet carpet to the dais, so quickly through strips of light and shade that they flickered red in my eyes. I passed haughty Awian eagles, rearing Plainslands horses and Hacilith fists between the arches. All the Fourlands’ heraldry was bold in the stained-glass windows behind the Emperor.

The sunburst, a solid electrum screen behind the marble throne, was polished to a mirror radiance and its rays haloed the throne for a metre on all sides. It rested on its lowest two points and, since the Emperor was sitting, his head was in the exact centre of the sun disc. Every beam extending out around him reflected me indistinctly as I approached.

‘My lord Emperor!’ I knelt at the foot of the dais, peppered with yellow light from the rose window. I was panting too much to continue.

The Emperor said calmly, ‘The Circle broke. Hayl, Thunder and Gayle are dead. Do you know what killed them?’

‘My lord, something awful’s happening. They were all at Slake Cross-and Insects are flying!’

‘Flying?’

‘Yes, my lord. A gigantic mating flight, over the lake and the town.’

I looked up, but the light was in my eyes and I couldn’t see the Emperor’s face. He sat in the shade under an octagonal marble vault that stretched high above him into the traceried interior of the spire, like the inside of a gigantic lantern. The white marble throne was imposing, but not so big that it diminished his form. His ancient broadsword and shield hung on its back. I was very glad I couldn’t read his expression.

His knurled hands, raised bone covered with ancient thin skin like batwings, uncurled from the scrolled armrests as he stood up. He came to the edge of the dais. ‘Tell me all.’

I recounted everything, and ended, ‘If the flight has stopped, the others will have cleared the town by now. There must be millions of Insect eggs in the lake…’ I hesitated, nervously. ‘Have I made sense, my lord? Have I been completely clear?’