The others followed, one by one, taking care to keep their distance. When all were in the air they manoeuvred into formation, signalled to each other with flags and then turned towards the west, to pick up the rest of the scrutators in Lybing. And then, on to the hunt.

The journey took days, though it was mostly uneventful, for which Ullii was glad. Used to shutting the world out, she found the proximity of so many hard, relentless people unbearable. She could not sleep in the great cabin, as the racket of chatter, snoring, belching and farting never stopped. On the second night she climbed onto the roof, found a recess sheltered from the wind and spent the night there, wrapped in blankets and coat. It was miserably cold but she was used to that. The air was fresh and the constant wailing of the wind blurred out the sounds of the fifty people below.

Only once during that journey did anything of note happen. It was about a week after they had departed Nennifer — Ullii did not count the days — and the fleet had just sailed high over the Sea of Thurkad, heading towards Meldorin Island and the ancient city of Thurkad, whose fall had heralded the loss of the west.

Ullii was standing at the bow, where the air streaming in her face protected her from the stink of unwashed humanity, when her keen hearing picked up Ghorr's voice, just outside the forward cabin door. He was talking to Scrutator Fusshte.

'Are you still going to give a demonstration?' Fusshte asked. His sibilant tones always made Ullii shiver, and the way he looked at her was worse.

'When I find the best target,' said Ghorr. 'I'll send a warning to our enemies not to take us too lightly.'

'And to our friends!' Fusshte chuckled nastily.

'Indeed' said Ghorr. 'There's not a single person on Santhenar who should not know what I can do, and beware! Fusshte took a step backwards, just managing to control his alarm. 'Quite,' he said smoothly. 'People have come to doubt the power of the scrutators. After this, they'll be in no doubt at all.'

Ghorr called the captain of his personal guard. The man listened carefully, saluted, then gave orders to his signalman, who began to pull his coloured flags up and down. After checking the acknowledgment with a spyglass, he reported back to the captain.

The air-dreadnought turned slowly. The others followed it, maintaining their formation, until they were heading directly for the southern section of the city of Thurkad. Ghorr consulted a plan and gave further orders, which the signalman relayed.

'Just there,' he said to the captain, pointing. According to my intelligence, many lyrinx house themselves in that one.'

They were now close enough for the largest buildings of Thurkad to be distinguished. Ghorr's outstretched arm indicated one of a series of tall wooden warehouses, built on the edge of the wharf city that formed the seaward rim of the city proper. Lyrinx soared in the air though, as yet, none approached them. This mighty armada would be the match of hundreds of flying lyrinx, and flew above the height they could reach.

Artificers now pulled the cover off a large metal mirror, the best part of two spans across, and swung it out. But it was more than just a mirror, for it had a complicated controller apparatus at the back, and an operator to use it. On the other air-dreadnoughts, similar devices were being moved into position.

More signals were sent. At the bow, a young woman in a green and grey uniform turned over a minute-glass. The air-dreadnought floated ponderously towards the target. The operator made continual adjustments to his mirror, reflecting the sunlight in a narrow beam across the bay, and then at the wharves ahead. The beams of the other mirrors followed the first, making a tight cluster of bright dots.

'Ten,' called the young woman. A man behind her raised a series of signal flags, one after another, as she counted down the numbers. 'Five, four, three, two, one. Now!'

The signalman swept down his red flag. The mirror operator stood up on his toes, drew power into the mighty controller crystals and pulled down a lever. The air-dreadnought shuddered.

Ullii felt a sickening feeling in the pit of her stomach as the field — what was left of it — tried to tie itself in knots. For an instant the rotors stopped completely, and there was silence, apart from wind whistling through the ropes and wires.

The beams of all sixteen mirrors converged on a single point, the top floor of the warehouse Ghorr had indicated. Suddenly they were amplified a thousand times by the power from the controller crystals. The bright spot became incandescent, burning straight through the tiled roof. The timbers erupted in flames and within seconds the roof, fifty spans long and twenty wide, was gone.

The bright spot moved down inside, fire leaping up after it, before smoke belching from the warehouse blotted it out. A single lyrinx fled out through the roof, one wing aflame, before wheeling down to smack into the water beside the wharf.

The smoke sucked back down momentarily; then, in a colossal explosion, the walls of the warehouse blew out, raining burning debris everywhere and setting fire to the neighbouring buildings. Burning lyrinx fled through the doors and windows.

'Must have been an old store of naphtha barrels in there,' Ghorr said with a grim chuckle. 'But we won't mention that in our reports, eh, Fusshte? Let the world think we did it all.'

The mirror operator was standing up in his seat, helmet askew, mouth agape.

'Marvellous,' said Fusshte in a choked voice. He cast a side-ways glance at Ghorr that told Ullii a lot. Suddenly, Fusshte was afraid of the chief scrutator.

Ullii became aware that the pilot was shouting. The rotors were still running irregularly and there was barely anything left in the field. Down below, a score of lyrinx tried to take to the air but none could get aloft.

Ghorr, Fusshte, and the pilot and operator had a hurried conference by the rail. With all the cheering, Ullii only caught part of it. They were worried by what had happened to the field.

'That'll have to be all,' Ghorr said regretfully. 'I'm not going to spoil a brilliant success by a failure. If there's no power there's no power. It'll look better if we just sail majestically on. Still, we've given them a shock they'll not forget.'

They drifted with the wind and, some leagues west of Thurkad, the operators picked up another field, though the rotors were still running irregularly. It appeared the surge of power had damaged something. Ullii was pleased about that. The ruin wrought by the mirrors had horrified her.

That night they passed over the mountains of Bannador, and the higher ranges beyond, which were covered in snow from top to bottom. 'Where do you think they are?' said Fusshte in the night. 'Shazmak? It lies south of our route.'

'Why would they go to Shazmak?' said Ghorr. 'They'll be somewhere where they can buy food, or hunt for it. Isolated towns survive in the north of Meldorin, I'm told, and on the west coast.'

In the morning they landed on a grassy plain, where they could see for leagues in any direction, though four of the air-dreadnoughts remained in the air, on watch.

'We're some little way north of the ruins of Chanthed,' said Ghorr, 'where the College of the Histories stood. The Plains of Folc lie north of us. To the west the plains run for fifty leagues into the Silbis Drylands. The western mountains lie beyond that, by the coast. Somewhere there we'll find them.

'Now,' he went on once the machine had settled on its triple keels, 'it's your turn, Ullii Find the traitor Flydd. Find Irisis Stirm, who lied to you and abandoned you. Find Cryl-Nish Hlar, the man who made you pregnant. The one who murdered your brother and destroyed your helpless baby. And then, lead us to them, so we can take your revenge for you.'