Riders galloped through the gap, voices hoarse, shouting orders to move.

'Ellin!' Avesh yelled. 'The Dord. Remember the Dord!'

'Mummy!' screamed Atyo, wriggling around, straining to see her.

Avesh saw her just once more, bobbing like a bottle in a stormy sea, helpless, unable even to struggle as she vanished from sight.

'Mummy!'

'It's all right, Atyo,' said Avesh, head down and running again, breath heaving painfully into his lungs. 'We'll find her. We'll see her soon.'

Right in front of him, a man tripped and fell. Reacting fast, Avesh hurdled the sprawling figure. His left foot came down on slimy wet mud and slipped sideways. Hopelessly unbalanced, he pitched right, holding hard on to his son as he went down.

The sound of horses was very close again. He rolled over, people scrambling past him cursing, shouts chasing them, that rhythmic thump of feet mingling with hoof beats reverberating through the ground.

Avesh clambered to his feet, presenting his back to the streaming mob threatening to knock him back down again. His muddied and terrified son was screaming, out of control, clutching handfuls of his clothing.

'We'll be all right,' said Avesh. 'We'll-'

He was standing in a space that suddenly contained too much horseflesh to dodge. He turned left and right, his vision filled with black and brown flanks, greaved legs and riding boots. He felt a heavy impact as a stallion reared near him, its rider yelling at him to move, but he could do nothing more than fall flat on his back.

He lay still, hooves coming down close to his head and body on their way past, driving the wailing refugees further and further from Xetesk. The relative silence flooded him. He gasped a breath.

'We'll be safe now, boy, safe now,' he said, stroking Atyo's head. His hand came away wet. Blood. He froze.

'Atyo?' The boy was limp in his arms. 'Atyo?'

He scrabbled frantically into a sitting position and held the boy in his lap. Atyo's head lolled to one side, blood matting his face. And, just below the hairline, his skull was stove in, caught by a horse's hoof. He had never stood a chance.

'No.' The word was barely audible. 'No.'

Avesh rose to his feet, holding his dead child to his chest. After all they'd been through, huddling in the intense cold, saving scraps of food from the ground and going days without. The boy had survived it all, only to be murdered by those he'd begged for succour.

The tears began rolling down his face, smearing the dirt as they came. Avesh fought back the nausea that swept through him, the blackening of his vision and the clouding of his mind.

His boy. Dead.

His vision cleared and he took in the litter of the camp, the scattering stragglers missed by the soldiers and the dozens, maybe hundreds, of prone forms lying where they'd fallen, clothes ruffling in the breeze. Some moved, most did not. And he saw the line of cavalry backed by the masked abominations that were the Protectors, their pace unremitting. Thump, thump, thump.

He looked down. He was standing on a tattered blanket. He laid Atyo on it and wrapped it around the boy's body. At least he wouldn't get cold. With a last look at that face so casually ruined, he kissed Atyo's forehead and closed the blanket. He stood.

The blank walls of Xetesk faced him. They could not be allowed to escape justice but he would not toss his life away in a futile attempt at vengeance. That would mock Atyo's death.

His body shaking. Avesh turned and walked away towards the north and the crossing of the River Dord, there to find his wife so they could bury their son together.

Then he'd be back. And he wouldn't be alone.

By the time they reached the canopy rope crossing of the huge sluggish brown force of the River Ix, Rebraal wasn't sure who was supposed to be rescuing who.

A night where they'd both slept long through sheer exhaustion had given way to two days where it seemed the rain was Gyal's tears, sweeping across the forest and drenching it almost incessantly. Sometimes it abated to a fine mist, but more often it fell in torrents with angry thunder cracking above the canopy.

Rebraal's shoulder was agony, his multiple cuts and scratches from being dragged to the pile of bodies by the strangers and away again by Meru itched in unison. They'd done what they could – legumia root paste for the deep crossbow wound, poultices of rubiac fruits for his scratches and long drinks of menispere to ward off the effects of fever – but he knew he was getting sick. He should be resting, not running home, wading rivers and climbing high into the canopy to use the hidden walkways and ropes to pass the great rivers and waterfalls.

His muscles were tortured, his back aflame with searing pain and his mind often muddied and confused. He'd mistaken bird and monkey calls more than once, had blundered into a swarm of ants and escaped a crocodile by a mere heartbeat.

But for all his many woes, his greater concern was Mercuun. His was a sickness that defied understanding or remedy and attacked him apparently at random, leaving him gasping for breath one moment and driven with manic energy the next, though the latter was becoming increasingly infrequent. Meru had assumed it was something in his stomach and they'd searched and found a good supply of simarou bark with which they made strong infusions, but it did no recognisable good.

Between his bouts of energy, he lost muscle strength and bulk, his balance was dangerously off true and, on the second morning, Rebraal had wakened to hear Mercuun coughing as if his organs were fighting their way into his throat. His friend could not disguise the blood that flew from his mouth in a spray every time he convulsed.

Later that afternoon, they'd rested long by the banks of the Ix, sheltered from Gyal's tears and prayed to Orra, the God of the earth's life blood, for an end to the illness that plagued Mercuun. Rebraal had looked at him where they sat close together under the great broad leaves of a young palm and seen death stalking across his face. He seemed to be collapsing from the inside out, and for all their herbal lore they could find no antidote.

'You're sure you haven't been bitten?' probed Rebraal, moving his back against the bole of the palm and feeling a new pain shoot through his legs and neck.

'I'm sure,' said Mercuun, his voice a hoarse whisper, his throat raw from wracking coughs. Every time he breathed, he shuddered.

'Have you checked yourself? If not a viper, a brush with a yellowback is all it would take.'

'It's not poison,' said Mercuun.

'Then what is it?' Rebraal was at a loss.

'I don't know.' Mercuun shook his head and lifted his face to Rebraal. He was scared; his eyes betrayed him and tears of frustration and fear welled up before he could catch them. 'Shorth is coming. I can feel it.'

'You aren't going to die, Meru.' Rebraal reached out a hand, which his friend grabbed and held tight. 'We'll be in the village before nightfall. There is help for you there.'

Mercuun dropped his head back to stare at the muddied ground. 'There is nothing their healers know that we don't.'

'But they will also employ magic should they have to,' said Rebraal, giving Mercuun's hand a reassuring squeeze before climbing stiffly to his feet. 'Come on. One more climb and it's all down from then on.'

But as he looked up into the canopy and their hundred-foot climb, his confidence wavered. He had seen Meru stumble over the merest root. And he himself could only rely on one arm. The other was as good as useless, the strength of his grip diminished by the wound in his shoulder.

'It seems so high,' said Mercuun, staring up and out over the river.

High above the muddy flow, where the canopy leant in on both sides, the practised eye could see a trio of tensed ropes among the leaves and branches. Used by elves and monkeys alike, the crossing spanned the one-hundred-yard width of the River Ix. Upriver, a waterfall more than five hundred feet high plunged into a huge sheltered pool, its outflow slackened by long lazy twists in the deep river. Way downstream, where the Ix narrowed, rocks hastened the water through a cramped ravine before the river spilled back out into its natural slow state. And everywhere along its length, death lurked beneath the surface.