Vassago's Canyon must have been where the black sandstorm had come from. It was a dark fissure in a desert of midnight-black dunes. 

But calling the sand black – or even midnight-black – didn't do it justice. It was the kind of shade that only needed a light shining on it to unleash a hundred different colours, all of them black, and all of them so much more: rose-black, moss-black, peacock-purple-and-green black.

At one end of the canyon – the end that Jack and the king were heading towards – a gigantic waterfall thundered down into the depths, foaming white and seething with compressed energy even before it hit the riverbed. At this distance, the roar was deafening. Jack could feel the sound vibrating in his chest.

This was the waterfall Sita had arrived by. The king told him that the Queen had stretched a net from one wall of the canyon to the other, in order to filter out anything of value that was being carried along the river's course. But Jack couldn't see it: everything was lost in foam and ferment. Apparently, it was staffed by demons who walked out onto the net, wearing protective clothing to shield them from the torrent, and picked up anything that had become entangled.

They had spotted Sita at once, the king said. She might not have sparkled, but it had been obvious from the first that she was a jewel.

She was at the canyon too, walking up and down one side of the crevasse with her gryphon – or sphinx, if that was what he was. She was still slightly transparent. Her feet didn't make any impression in the black sand. 

The roar of the waterfall was quieter here. Girl and gryphon seemed to walk the bounds of a little charmed circle which the commotion couldn't reach. At the centre of the circle was Sita's body, propped up on a pile of wood and sticks and grasses that looked like a funeral pyre, but which Jack was willing to hope was just the gryphon's nest.

In fact, it was so quiet that he could hear the little body breathing – which it did with a strained, raspy, sucking sound that drew her whole chest upwards. All the life in that body seemed to be concentrated in that desperate act of breathing. He wondered how long it could go on for.

It should have been the gryphon that drew his eyes, perhaps – although at least he was in-keeping with the landscape. He was a massive, shadowy edifice of a thing – winged and hairy and clawed. But there was a padding delicacy to his movements, and his lion's face was gentle, even though it ended in a cruel, hooked beak.

The Queen was standing a little way off, looking down on them. Jack could only see her back, although that was more than enough to be getting on with. It was almost laid bare by the sheer black lace, and it was lithe, shapely, and muscular. Her golden skin shone in the firelight and made her look like some kind of heathen idol. 

She was holding a torch that appeared to be made of bone, with oily rags wrapped around one end and blazing merrily. She was letting it droop, though. It had dipped almost to the level of the sand by the time Jack and the king reached her, presumably because she was so enthralled by Sita's conversation. 

What was so important there? What was it that was engrossing her? Just a riddle, and a child's childish efforts to answer it. Sita had been asking the gryphon to repeat it when Jack and the king got close enough to hear, and he had sketched it out like this:

"Poor people have me, rich people want me, and, if you eat me, you'll die. What am I?"

"Poison," said Sita, with a promptness that made the gryphon blink.

"Why would rich people want poison?" he asked. He had a strange voice: purring and ponderous, gentle but ageless, as if you were to find a sense of humour in a rock-face.

"So they can dispose of their enemies," said Sita. "'Cause they're rich and they can get away with killing whoever they like."

"And poor people have poison-?" the gryphon prompted.

"Yes, because they can't afford clean drinking water or carbolic soap, and they have to share a privy with twenty other families, so they get poisoned by their own filth – that's what mama says. She says, in the rookeries-"

"The answer I usually give," said the gryphon, his eyes closed with cat-like inscrutability, "is 'Nothing'."

"Oh," said Sita. "I see. 'If you eat me, you'll die'. Hah." She sniffed, and went on, "But it's rather a materialistic solution, isn't it? I mean, rich people might want lots of things – like patience and tact and imagination. And who's to say that poor people have nothing? They might have love, or faith, or virtue-"

"And what good are those things," said the gryphon, "when you are being poisoned by your own filth?"

Sita squinted at him. "Is this another riddle?"

"If it is, I do not have the answer."

They walked on in silence for a while, Sita swinging her arms in that way Jack had already come to recognize. He was, by now, hanging on their every word. Their little conversation felt as wholesome as the sea-breeze through an open window. They seemed to be the only creatures in this place that didn't come from inside his head – or, anyway, that weren't being influenced by the contents of his head.

And then he looked at the Queen – at the way her shoulders rose and fell as she breathed – and wondered if it was just as wholesome for her. Perhaps she had not seen innocence in a long time. It was funny, the way it called to you, for all its practical uselessness.

"I win, don't I?" said Sita at last. "You can't say my answer didn't fit, or that yours was perfect."

"I cannot," said the gryphon.

"So I win?"

"You do not lose."

Sita swung her arms again, perhaps to celebrate. "Are you one of those Spinxes who throw themselves off a cliff when someone guesses their riddle?"

"Clearly not," said the gryphon.

"Do you know Eddypuss?"

"Oedipus? Yes."

"That's what his Spinx did."

"Yes. But she also strangled and devoured anyone who failed to guess her riddle, so it was really only fair."

Sita hesitated, and Jack wondered whether this unsavoury detail had been omitted from her version of the story. Still, if you were going to omit unsavoury details from the story of Oedipus, what would there be left to tell? The gryphon seemed to be thinking along the same lines, because he said, "You know of Oedipus, then?"

Sita shrugged, as though unwilling to admit her ignorance. "He behaved very wrongly to his mother. I couldn't get Leeny to be more explicit than that."

"I fear you will find the same reticence in me."

"I never expected to find anything else," Sita grumbled. "Reticence is all I get from anyone over the age of nine."

"And I am nine hundred and seventy-two," said the gryphon supportively.

"Oh," said Sita, as if she was being told the answer to another riddle. "You'll be able to have a big party in twenty-eight years. When you turn one thousand."

"Yes," said the gryphon. "I am looking forward to it."

"Will you invite me?"

"I would be honoured."

"I expect I'll be an old lady then, but I can make seedcake. I thought you'd like seedcake," she added generously, "because of your beak." Jack thought it was nice of her not to mention that the gryphon had the kind of beak that tore, not the kind that pecked.

Yes, she was an incentive. She was a jewel. The king really had helped him as much as he'd been able – and, whether or not he'd done it for the sake of his own entertainment, Jack couldn't help feeling grateful. He had been wanting to fight for the innocent all his life, even though he'd never had much in common with them, and they never really seemed to want his help. But Sita was different. She was so like him, in every respect except the sneaky, angry, violent respects – the respects that didn't know the meaning of the word 'respect'.

"Enough," said the Queen, moving very suddenly, and striking the torch into the sand at her feet. It stood there, lopsided and flickering, while she oiled her way forwards. Sita and the gryphon paused in their circuit and looked at her, clearly afraid they had done something wrong.

"Sita, my dear," said the Queen, smiling sweetly, "you have been very patient and very kind to answer riddles for my amusement, but I wonder if I might prevail upon you to answer one more? What does this man want with you?"

She pointed at Jack. She hadn't glanced at him, he would have sworn to that, but perhaps she had sensed him from the pounding, squirming noise his heart made whenever he stood near her.

Sita looked at Jack, as if beseeching him for a clue. "Um. He wants to bring me back to my sister, your Majesty."

"And do you trust him to do so?"

"Oh yes," said Sita, nodding vigorously. "He loves her ever such a lot. He once punched our house-"

"And should you like to go with him, my dear?" said the Queen, kneeling down beside her to be level with her face. It was a kind gesture, no doubt, but the physics of this movement with the sheer black dress compelled Jack to shut his eyes. "Should you really like to leave us?"

Jack heard, from behind his clenched eyelids, the little girl struggling with the delicacy of the situation. "I should... like to see my sister again. If you please, ma'am."

"Enough," said the Queen again. Her voice sounded raw and unpolished now – not at all the sweet, wheedling, smoky sound that had been calling to Jack's flesh from the moment he'd arrived.

"You will help him to run the gauntlet, my dear," said the Queen. "Do you know what that is?"

Jack opened his eyes, to see Sita looking up at the gryphon. It was obvious from the creature's gentle, leonine face that he knew, but he wasn't saying anything.

"A sort of challenge?" said Sita. "A lot of challenges?"

"A lot of challenges," the Queen agreed. "And you will partake of his failures."

"What does that mean?" said Jack sharply. It felt like a long time since he had last used his voice.

The Queen ignored him and went on addressing Sita. "Do you trust him enough to bind your fate to his like that? I mean, what do you know about him, really? Do you think you can trust him because he loves your sister? Didn't the man who put you here also love your sister? And aren't you tired, after all that, of everyone putting your sister first, and you second?"

"Leeny doesn't put me second," said Sita, jutting out her chin as if the Queen had been quite rude. "It's not her fault she's prettier. And this man-" she pointed at Jack- "says that, in the future, she's very sad, and not at all to be envied, so I'd like to go and comfort her, if I can. I don't know much about him, that's true, your Majesty, but he's here, and-" She shrugged helplessly. "And nobody else came."