Most seemed to have no input or output, which puzzled Tiaan mightily. She understood how a clock could be driven by a spring that eventually moved the hands, or how a mill powered by water could turn a grinding wheel. With these devices, she could find nothing to make them go in the first place, or what work they were supposed to do when they were going. And at the far end of the room, equally strange, was mounted an enormous metal slab, five spans high and three wide. It had no discernible function.

At least a day went by without Tiaan having catalogued the machines or worked out which ones she was to take parts from, or which connected to which. Tirthrax had few windows and the lightglasses stayed on whilever she was in the room, so she had little idea of the time.

Realising that it must be late, she looked around for Haani. The child was nowhere to be found and Tiaan could not remember when she’d last seen her. Certainly it had been hours ago. She went to the door. Haani was not visible. Where could the wretched kid have gone?

Tiaan called her name but there was no reply. She wandered across the floor of that vast space, her boots echoing. The child could be in any of a thousand rooms. She might have become hopelessly lost, or fallen down a shaft. Her mind roved over the infinite possibilities for disaster.

‘Bother!’ she said aloud. ‘I don’t have time for this, Haani.’

A childish shriek, high up. Tiaan ran screaming, ‘Haani? Where are you? What’s the matter?’ Why, why had she left her alone? Maybe some mountain predator lived in here. It was a perfect hideout. Now it had her and it was all Tiaan’s fault.

Another shriek came floating down but this time she recognised it for what it was. Haani was shrieking with laughter. Where was she?

As she scanned back and forth a movement caught her eye, a flash through the hole, at least twenty spans above, where the spiral staircase went up through the ceiling to the next level.

‘Haani!’ she shouted, thinking that the child was falling.

Haani shot around in a spiral. She wasn’t falling at all – the little wretch was riding the metal banister, swirling round and down like water going down a plughole. If she went off the edge …

But Haani did not. With a series of whoops and shrieks she slid the rail all the way down, shooting off the end and skidding across the smooth floor. ‘Whee!’

Tiaan came running. She did not know what to say; she wanted to smack Haani, to yell at her to never do such a stupid thing again. Tiaan did neither, just stood with her arms hanging down and the terror frozen on her face.

Haani looked up at Tiaan’s expression and the joy ran out of her. ‘What’s the matter?’

‘I …’ Tiaan gulped. ‘I thought some wild beast was eating you. And then, when I saw you, I was sure you were going to fall and be killed. Oh, Haani, I was so afraid.’

‘I was having fun. I wasn’t going to get hurt. You just don’t want …’ She broke off.

Tiaan knew what she had been going to say. It saddened her because it was perfectly true. She cared for the child deeply but at the same time found her a burden, and resented her for it. What a selfish cow I am, she thought. She asks for so little, and even that I am incapable of giving her.

‘Haani, I didn’t want anything to happen to you. I love you too much.’ It was true, though Tiaan only now realised it. She loved the child more than her own half-brothers and -sisters. More than her mother. More than anyone except Minis.

‘You love me?’ Haani whispered.

‘Of course I do. Come here.’ She held out her arms.

Haani stood unmoving. She took a step forward, stopped as if it could not possibly be true, took another step then flung herself into Tiaan’s arms.

‘I love you too,’ she said in Tiaan’s ear. ‘You’re not my mother though.’

‘No.’ Tiaan found tears in her own eyes. ‘I can’t be your mother, can I?’

‘I had a mother, but the nylatl killed her.’

Silence.

‘What would you like me to be, Haani? An aunt; a friend?’

‘I had aunts. The nylatl killed them too. And …’ She looked up at Tiaan. ‘You’re too old to be my friend.’

‘How old do you think I am?’

Haani studied her. ‘Really old. At least fifty.’

‘Fifty? You little wretch! You need a good beating for even thinking such a wicked thing.’

Haani stepped well back, though she did not look alarmed. ‘How old are you?’

‘I’m twenty, as it happens. I’ll be twenty-one very soon.’

‘When is your birthday?’

Tiaan calculated. It had been two and a half weeks away when they left Itsipitsi, eleven days ago. ‘It’s not tomorrow, or the day after, or the three days after that, but the day after that. It’s in six days’ time.’

‘Twenty-one.’ Haani seemed to be weighing up the numbers.

‘I could be your older sister.’

Haani considered that. ‘I’ve always wanted a big sister.’

‘Well, that’s settled. I’ll be your big sister.’

Tiaan gave her a sisterly hug; after a moment Haani pulled back, saying, ‘I’m hungry.’

‘So am I. Let’s have our dinner. I don’t suppose you found any water?’

‘Way down there!’ She pointed, then held out her hand. ‘Come on! I’ll show you.’

Tiaan took the hand. They ran and skipped across the chamber, where a room had implements recognisable as taps. Haani wound an S-shaped lever and water gushed from a spigot. She tried the other with the same result. Tiaan filled her pot. They sat on the floor, eating cheese, onion and very dry deer meat.

‘I wish we had something different, for a change,’ Tiaan said. ‘We’ll have to see if any food was left behind.’ She was worried. They had enough for a week and a half, or two if they really stretched it, but what then? It was a long week’s trek to Itsipitsi, and nothing to buy food with when they got there. If this place had been abandoned for years, perhaps centuries, there was probably nothing edible here either.

‘I can look while you’re doing your work,’ the child said.

‘All right, as long as you don’t go too far. And don’t do anything dangerous.’

‘Of course I won’t.’

They slept in one of the few rooms with a window, so they’d know when it was morning. That seemed to matter, somehow. At first light they breakfasted, went exploring but failed to find any food. On the way back, Haani put her head in through a doorway and said, ‘What’s this place?’

‘A bathroom, I’d say. Want to try it?’

‘What is a bathroom?’ Haani asked.

Tiaan explained. It was a curious one, for when Haani wound the taps water sprayed out of the walls and ceiling. ‘I think you’re meant to stand under the water and wash yourself,’ Tiaan said.

The water was not unpleasantly cold; better than they were used to. Haani was about to get out when she said ‘Hey!’ and put her hands out against the spray.

‘What’s the matter?’

‘It’s … getting hot.’

Tiaan eventually got the flow adjusted so that it was just perfect. What a luxury! Not even the breeding factory had hot water coming out of a tap. It was the ultimate mark of civilisation as far as Tiaan was concerned, far more impressive than the architecture outside, or the extraordinary machines.

The following day Haani was busy on some project that she carefully kept secret. A birthday present, Tiaan guessed. She went back to the room with the three sentinels and began dismantling the machines. She could recall each of the images Minis had shown her, and how she was to put everything together. Remembering was the easy part.

She made a start. Without proper tools, it was abominably difficult. By the end of the day she had not taken apart the first machine. At this rate it would take weeks. Minis would be dead by then, and so would they; of starvation.

She sat down, wiping her brow, for the room was warmer than the rest of Tirthrax. Haani came running in. ‘Look what I found!’