At the river I altered my course, heading upstream to the dam. Bulrushes bowed to the water’s creased surface as the wind ruffled through reed beds on the south bank. Its other bank was nothing but mud mashed with three-clawed footprints: Insects had stripped the vegetation bare.

Frost’s workings began and the ground changed abruptly. Her company had done nothing less than remodel the valley. Cart tracks criss-crossed the bank; water in their ruts reflected the sky. Broken shovels, dirty string and red striped ranging rods littered the ground, with abandoned workmen’s huts, empty burlap bags, splays of spilt gravel.

The overturned earth was glutted with beige specks-calcined bone fragments-some recognisable as ribs or skulls; the remains of generations of men and women. There were pieces of archaic armour and broken Insect shells, which don’t easily decay but weather to porous shards. The Insects have been creeping or swarming southward over fifteen hundred years. In response, we constantly move men and supplies to the front to stop them, on such a massive scale that I fancy all the Fourlands will eventually erode and end up here as a series of hills.

The river banks straightened, reinforced by walls of metal mesh boxes full of rubble. The river flowed more slowly but its level had hardly dropped. Frost couldn’t allow it to dry up because, since Insects can’t swim, the Oriole River was our main defence.

I approached the dam from the front, its stone face a gigantic sloping wall. The ends tapered down and curved towards me like horns. The outflow hole at its base looked like a giant blank eye. A fortified winch tower stood on the crest above it, holding the mechanism to raise the gate. The walkway ran through the tower, blocked with formidable portcullises on entry and exit, so Insects could not cross from the Paperlands.

Lightning and Eleonora were two tiny figures beside it, looking down from behind the split-timber fence. The wind’s speed was increasing over the smooth outflow platform. Air hit the wall and hurtled up its slanting surface. I lay with my wings outstretched and let it carry me-square blocks and mortar streaked down past my eyes-I could have filed my nails on them.

Along the whole length of the dam the wind went rocketing up the incline faster and faster until it burst vertically from the edge of the walkway around Lightning and Eleonora and up into the sky.

I soared rapidly past them, hearing the last exchange of their conversation, ‘-This could be the answer.’

‘Perhaps. I just wish that we’d thought of it before.’

I found the right balance to hang motionless above their heads. My shadow fell over them and my boot toes dangled at the level of their faces. They drew back and shaded their eyes, seeing me suspended in the middle of six metres of glorious wingspan.

The enormous lake formed from the backed-up Oriole River spread out behind the dam. On its north bank the water lapped and merged into the mazes of Insects’ paper cells; irregular, many-sided boxes ranging from the size of a cupboard to that of a house. Passages wound between them, some covered with pointed roofs, the rest open to the air. They looked like ceramic fungi, or geometric papier-mâché termite mounds.

The lake stood cold and mirror-reflective in the fresh morning light. A swathe of ripples dimpled across its middle, broken by white, angular peaks projecting from the surface: the tops of flooded Insect buildings.

Insects had built and abandoned walls five times as the water level rose. Their tops contoured the irregular lake margin like tree rings. Our old camp and the shakehole that destroyed it were somewhere on the lakebed, completely papered over.

I could just see the Insects’ new wall on dry ground ten kilometres distant, beyond the marshes. They had instinctively joined the new stretch to the immense Wall that seals them in, protecting their Paperlands from coast to coast of the entire continent.

I let the wind blow me backwards over the walkway. Little by little I flexed my wings closed and descended. I bent my knees, absorbed the shock, and landed in a crouch with my stiff feathers brushing the paved track on my either side.

I stood and bowed to Queen Eleonora Tanager. She kissed me on both cheeks and studied my face at leisure. ‘How are you, darling? Oh, Jant, flying makes you so cold.’

Her attar of roses perfume enveloped me, calling to mind the rose-scented letters that she used to send. They were always crinkled and salty, having been written on her most recent lover’s sweaty back. Eleonora was arguably the world’s most powerful mortal, but she was shod with scandal; she was no good at delicacy and even worse at tact.

I stepped away and looked at the reservoir’s breathtaking expanse. ‘It’s incredible,’ I said. ‘I admit I had my doubts. But from up here you can see the extent of Frost’s vision. I feel privileged to be part of it.’

Lightning, the Castle’s Archer, said seriously, ‘Well, I hope it is not just the latest of the thousand plans we have tried and had to put aside.’

Eleonora shivered. She was wearing Lightning’s long, fur-lined overcoat and, statuesque as she was, it nearly fit her. Her scale armour glittered underneath. Awians sometimes wear full plate, but prefer their traditional scale mail and I can understand why because plate is horribly restrictive.

She had tipped her helmet back from her head and it hung upside down from a strap showing its green satin lining. It had eye holes and a nosepiece in the Awian style. Its copper-pink horsehair crest rustled against her back and nearly touched the ground. Her chain mail coif and scale shirt were copper-coloured too, and damascened with a raised pattern of feathers matching her greaves and vambraces. She had pulled out her satin undershirt a little between each joint.

Eleonora had a wide, prominent face with a delicate, tip-tilted nose. I should say she was good-looking but she had a sly and filthy smile. Her ecru wings were naturally a different colour than her close-cropped dark hair, a phenomenon so rare I had never seen it before.

I said, ‘Queen Eleonora, I don’t know if you realise the time but you’re already late for the press conference and Frost sent me to call you back.’

‘Oh, I suppose we must attend,’ she said huskily. She set off along the walkway, between the sheer drop on one side and the lapping water on the other. She strode with a slow, shapely-legged pace; from the deliberate way she carried herself it was clear she was used to being looked at.

She continued to enthuse as we joined her. ‘If this works we have a way of destroying the Paperlands completely. The effect’s there, right before our eyes! The Insects move out of the flooded area, make a new Wall and retreat behind it. Of their own accord, without any resistance!’

‘Then we drain the area and in we go!’ I said.

‘Let us concentrate on clearing this patch first,’ said Lightning.

Eleonora smiled. ‘It all depends on infantry. We’ll position them while Frost empties the lake. Isn’t that right?’

‘Yes.’ Lightning indicated the town squatting in the mid-distance. A constant queue of mules and baggage carts plodded towards it, bringing provisions and tackle in preparation to set up the camp that would soon be surrounding it. Outriders protected the convoy, riding in formation at specified distances from the road as soon as they entered Lowespass. We had not yet mustered the main body of the cavalry, because they consume a tremendous amount of fodder. In the other direction a tumbrel cart of manure was setting out from the stables towards the pine plantation. ‘We will position twenty battalions of Select, wielding axes, there…and there.’

I said, ‘It’ll be very muddy once they start to march.’