Wind acrid with smoke blew hard against Carnelian's mask. He felt his aquar slowing. He could make out that the ramp he had been riding up from the canyon floor ended abruptly in a promontory. His aquar's narrow head angled up and back, flaring plumes, as he yanked it to a halt. The plume fans folded and he saw the gloomy nave of the canyon. Its slope milled with traffic. Far above, the sky was an improbable painted ceiling.

The scrape of claws made him turn to see the Masters sweeping up with Aurum at their head.

'I will take responsibility for the Lord Suth.'

'You will not,' Carnelian said.

Aurum came very close to tower over him. Carnelian straightened his back and faced him. Aurum flicked the air in anger and turned his aquar, bellowing commands that sent the Marula hurtling past onto the road grooving off along the left-hand canyon wall.

Jaspar came up. 'Why have we stopped, my Lords?'

The Marula are the danger now,' said Aurum, the eye-slits of his mask following the black men as they grew smaller and smaller in the groove road.

Carnelian glanced up the length of the canyon. The sound of water made him look down to see the canal. 'A river,' his voice said.

Jaspar snorted. The vermin in the city below call it the River of Paradise. We call it the Cloaca. It is the sewer of our hidden land.'

'We ride to the Green Gate.' Aurum left the words behind as he launched into motion, leaving Carnelian and the other Masters to chase after him.

Rock was hurtling past his head. The canyon narrowed into the distance where, in a gloomy haze, it turned abruptly southwards. All the way to this bend, the floor was a dusky swirl of wagons and people divided in two by the groove of the Cloaca. A scraping scuffling shook up the canyon walls and set Carnelian's teeth to grinding. In the wind, his cloak became like a trapped bird struggling to escape. Up ahead Carnelian glimpsed the bladed edges of the canyon reaching high enough to graze the sun. It seemed impossible that any light should ever find its way down to the floor.

As they sped round the canyon's bend, Car n elian watched the next stretch coming into view. Billows of smoke rolling towards them engulfed the Marula, then broke over Carnelian till he was riding blind. He choked on the grey air. The clouds thinned enough to show the insect crowds below. Coughing, eyes welling, he tried to peer through the murk. He swam out spluttering as the smoke dispersed like morning mist. They had come to the prickling edge of what seemed to be an impenetrable forest.

The Green Gate, at last,' cried Jaspar.

Staring at the forest, Carnelian realized it was made of bronze, a bladed hedge shaped into a fortress wall that filled the canyon from side to side. The canyon floor was striped and chevroned with wagons covering these patterns in ordered files. Along its centre, the Cloaca had sunk into a chasm spanned by bridges.

Carnelian could see no way through the bronze hedge. Tall banners burned red among the thorns. Other flames appeared and became figures shrouded in vermilion. Some were as small as children. All were enveloped in cloaks that brushed the ground.

As Aurum's mask looked back, Carnelian followed its gaze. The Master was studying the Marula who had fallen behind them in close escort. Their faces were wooden with fear. Mouths hung open as if they were panting. Their eyes fixed on their hands. Tain was there between the legs of a Maruli, slight, unblinking, like a doll.

Dread began stirring in the pit of Carnelian's stomach as he watched the vermilion figures forming into a crescent. He looked at their faces. Each was the same, each divided, half skin, half black. He drew back into his chair as they threw back their cloaks. All wore gold legionary collars. Their leather armour was baroquely textured on the same side as their faces were black and on the other side as smooth as their skin. On each chest was a red flower like a flame. Each man's right side look charred, the left of each was barbarian brown.

'Ichorians,' he breathed. All his life, he had heard tales about these half-tattooed men. The Red Ichorians, guardians of the Three Gates.

One of them stepped forward lightly, like a dancer. He stood smiling before Aurum's aquar and then performed an elegant prostration.

'Surely you are Masters,' the man said, rising to his knees, 'though you wear no cyphers, no banners, nor are you guarded by tyadra. And those,' the Ichorian stabbed his black-tattooed hand towards the Marula, 'those creatures defile this road.'

Aurum pulled back his cowl to reveal the mask beneath and as he did so all the Ichorians knelt except the one in front of him who rose, still smiling.

'You're correct, Ichorian, in all you say,' Aurum said. 'We've come far through many perils and have had need of these disguises. Now we'll happily discard them.'

'We've heard that a party such as this accompanies the Master, Our-father-who-goes-before?'

Aurum lifted his hand in the affirmative and the Ichorian searched eagerly among the shrouded Masters. 'We expected you on the leftway, my Masters. Are you desirous to pass swiftly through the Three?'

Aurum repeated the affirming gesture. 'But first there's one matter you must attend to, centurion of the Red Lily.'

There was a clack as two Marula chairs struck together. Aurum's mask turned slightly to one side as if he were listening for more collisions.

'We aren't yours to command, my Master, unless you wear the Pomegranate Ring.'

In answer Aurum pushed his white hand out of his sleeve and splayed it. The ring was a huge wound in the heart of his palm.

'Father,' the Ichorian cried and fell before him onto the pavement. The cry was taken up by the other Ichorians. The centurion rose up again to his knees. 'Forgive the children that didn't know their father.'

Aurum turned his aquar so that he was looking back at the Marula. Carnelian followed his lead. Hunched in their saddle-chairs, the black men were huddling their beasts together. One of them who dared to look up had the shy look of a child expecting punishment.

Aurum lifted his hand and pointed. 'Destroy those animals.'

'Destroy them,' chorused Vennel and Jaspar.

As one, the crescent of Ichorians swept forward, passing quickly between the Masters to face the Marula. The black men's faces creased with panic. One of the guardsmen lifted his tattooed hand. In his grip was a bird of bronze winged with blades. He released it into whistling flight around his hand. As he let out its leash its blurring circle widened with the eyes of the Marula. Their lances wavered out in front of them as they backed their beasts away. The bladed bird began to keen. Other Ichorian arms were whirling similar weapons. Their keening modulated together into an eerie discordant chorus. The Marula began raggedly wailing as the first blade hurtled through the air. A Maruli slapped into the back of his chair, the blade deep in his throat. His lance angled lifeless. The line that held the blade yanked back and the Maruli's head lolled forward, bounced on the dead man's knees and thudded to the ground arcing blood. The air was sliced by more blade flights. The Marula ducked frantically but there was no place to hide. The aquar made cries like tearing metal, their flaring plumes were scythed like flowers. A hand flew off that was being held up as a shield. Screams were choked to gurgling. Carnelian looked down with horror and saw heads thudding to the ground like overripe fruit, rolling red trails. When he looked up, the headless trunks were jerking as the aquar milled bleating, blood welling in their saddle-chairs and spilling down their flanks.

Carnelian remembered Tain with a gasp. Quickly untying his father's reins from his saddle-chair, he threw them over to Jaspar and then forced his aquar into the maelstrom. Warning cries from the other Masters seemed remote. Everything was moving as slowly as curling smoke. As he ground his eyes round, Carnelian saw one of the Ichorians, only a boy, tugging twice on a line; it bellied back dragging its blade. Blood flicking off it across Carnelian's hand was pleasantly warm. His aquar's steps pumped him lazily up and down. He saw Tain sitting stiff and bloody, eyes screwed shut, clamped in the arms of a headless black and red man. An Ichorian placed himself in Carnelian's path mouthing something. Carnelian urged his aquar on and watched the man jump out of his way. He lifted his gaze, saw Tain, leaned precariously out and prised him from the corpse. As he fell back into his saddle-chair, his brother's weight crushed out a grunt.