‘As you all know,’ Ma’am said at muster, ‘tomorrow evening is the graf’s birthday ball. So after your normal duties tomorrow everyone must stay late. Isolde has the roster, so see her to find out your assignment. Dismissed.’

‘You’re to present yourselves to Mrs Quilty, early afternoon tomorrow,’ Isolde told them when they finally got through to her. ‘She needs you for tables. Tomorrow night you can stay over in the attic rooms; we don’t want you going home in the middle of the night. Be sure to tell your mothers.’

Mother left for the laundry, and Piri went with Moni to Countess Sabra’s apartments. Isolde had a large empty trolley. She passed the handle to Doncia and curled a finger indicating she should follow. They headed past the hall with all the paintings and into the east wing, where Doncia had never been. A large robot sweeper almost filled a dingy service room. Isolde unplugged it from the charging socket.

‘Help me drag this lug of a thing out.’

With Isolde’s muscles bulging, and Doncia pushing from behind, they manoeuvred the heavy robot into the corridor. Isolde tapped the red button on the top, and whirring sounds came from inside. It rotated its turret completely and lifted on its legs. It clattered to the left a few paces, clattered back, then settled back down.

‘Just like yesterday,’ Isolde said. ‘That’s the basic locomotion test, and it seems to be all it can do. I want you to take it to the technologicians for repair.’ She pointed to a position on the floor. ‘Move the trolley here.’

‘Yes, Isolde,’ Doncia said, and wheeled the trolley to the left of the robot. Isolde tilted the trolley and extended a leg so it formed a ramp. She then grabbed the trolley handle and readied herself to hold it steady.

‘Smack the button, and when it is in the trolley, before it walks back off, smack it again.’

Doncia stretched up and hit the button, and the robot clattered up the trolley while Isolde braced it. Doncia hit the button again, just in time. It stayed on the trolley.

‘Well done. Now, do you think you can manage to take this fellow all the way along the blue corridor, that’s this one we are on, past the middle tower, right to the end tower, then left all the way to the repair station at the far end?’

Doncia was excited, and grateful.

‘Yes, Isolde,’ she said. ‘Thank you for trusting me again, after yesterday.’

‘Well, there’s no one else. Just don’t wander—take it there, explain what is wrong, wait for it to be repaired, if they can, and bring it back to the muster room. Don’t leave the blue corridor.’

‘Yes, Isolde.’

Isolde gave her a steady look.

‘I won’t leave the blue corridor.’

‘All right. It shouldn’t take too long. If you are not back by mid-morning I’ll come looking. Make sure I don’t need to.’

Doncia nodded, and started to drag the trolley. Once it was moving she was able to progress quite well. The corridor was just like the others, with archways leading to splendid halls, and closed doorways leading who-knows-where. Stuffy old men stared lifeless from paintings; she assumed they were the graf’s ancestors. The pale blue frieze stretched along the bottom of the walls, reassuring Doncia she was on the right course.

A tall, extremely fragile looking vase perched on a stand to one side. It was glossier than a mirror, and the bluest of blues, with a regular foliage pattern extending up the narrow neck. It seemed to be saying knock me over, go on, I’m only here to cause you trouble. The walls started to look a little orange.

‘No chance,’ Doncia said to the vase, and paused until the walls resumed their proper colour. The vase seemed to ring with anticipation. The robot was wobbly, and there was a carpet on the floor she had to pull the trolley on to. When the wheels hit the edge of the carpet she steadied the robot with one hand, and kept hold of it until was finally off the other side of the carpet.

Doncia wiped her forehead with the back of her hand, and continued on. An arch opened on to a tower staircase. Half way, she thought with relief.

Maynard bounded down the stairs, with his eager look.

‘Hello! What’s up with the robot?’

‘Isolde said to take it to the technologicians.’

‘I can help,’ he said. ‘I owe you...after last time.’

Doncia was anxious, she didn’t want things to get out of control. She’d promised Isolde.

‘I’m doing all right.’

‘Yes, of course,’ Maynard said, ‘but you can trust me. I’ll just steady it as you pull, and push if you need.’ His smile convinced her.

‘All right, thanks. Just go slow.’

‘Absolutely.’

Maynard was a tremendous help; they inched past statues and potted plants with ease. They turned at the second tower and soon arrived at a wide arch. The doors were latched open.

‘Here we are,’ Maynard said.

‘Thank you so much,’ Doncia said.

‘No trouble at all. Now, bring it in and let’s have a look.’

She stared at him, he wore a laboratory coat over a green linen suit. ‘Are you a technologician?’

‘Well, I’m learning,’ he admitted, ‘but I can certainly do an initial inspection. Come on.’

They towed the robot onto the dusty boards, and it wobbled a little on the uneven surface. Two men looked up from strange contraptions, and greeted Maynard.

‘What do you have there?’ the oldest asked.

‘It’s an early K12,’ the other one said, before Maynard could answer. ‘Junk.’

‘Don’t worry about them,’ Maynard whispered, and led her between the benches to a cramped area at the far back. Gaslights burned, but there was much in the way to cause shadows. Doncia couldn’t keep her mouth from hanging open, everywhere she looked unfamiliar machines rose from the gloom, most of them with half of their workings removed or hanging out.

‘Leave that,’ Maynard said, nodding at the robot, ‘and come see my latest project! It’s secret, mind. You must swear not to tell a soul.’

‘I swear,’ Doncia said lightly.

‘No, really, you mustn’t tell,’ he said. ‘It’s for the graf’s invention competition—totally secret until the unveiling at his birthday ball.’ He stared at her, his blue eyes sharp.

‘I promise, really,’ she said.

‘All right. It’s this.’

He pointed to a shiny metal box almost the size of a human head. Hundreds of screws held it together, far more than seemed necessary.

It wasn’t impressive. ‘What does it do?’

‘Well,’ Maynard said, ‘it’s best to show you.’

He opened up a cardboard carton of what looked like dirty rocks, chose one, dusted it off, and placed it on the bench. Then he turned over his metal box to reveal the bottom cover was missing. He placed the rock inside then screwed a cover on. The cover had a rod and wires protruding. He connected the wires to a device, and turned the rod, as if making an adjustment.

Nothing happened.

‘That’s odd,’ he said, and stared at her, as if the answer was in her face.

Doncia looked back, keeping all hint of a smile away.

He held up a finger, meaning wait a minute, and fiddled with some dials on the device with the wires.

The bench creaked and then there was a louder crack.

‘Oops!’ Maynard cried, then rushed to twist the rod.

The metal box and its beams raised a foot into the air, floated there for a moment, and then fell with a crash.

‘Wow!’ Doncia said.

‘Quite special, isn’t it?’

‘You can make a box fly,’ Doncia said, ‘for a little while.’

‘Well, that’s a problem at the moment.’

‘And coming down again is a problem. It’s like it can’t hear how high it is.’

‘It can’t hear?’ said Maynard, looking perplexed. Then he shook his head. ‘But you can see the potential?’

Doncia did. If he could make the box stay up, then he could make something fly without wings.

‘How much can it lift?’

‘That depends on the strength of the anrenn—the rock.’

‘It’s not just any rock?’

‘Of course not. It’s an anrenn, mined at Braxa. It’s like the ones in the robots.’

‘There are rocks in the robots?’

‘It does sound odd if you say it like that, but yes, not just rocks of course—anrenn are crystals, special crystals. They just sometimes happen to be hidden inside rocks, and often you don’t need to take them out of the rocks to use them.’

‘Do they all come from Braxa Mine?’

‘Most of them, all the new ones, anyway,’ he said.

‘How did they get there?’ Doncia wondered aloud.

‘You ask the oddest questions, Doncia,’ he said. ‘I’ve never asked anyone, but I think they’ve always been there.’

Doncia wondered if there were anrenn inside her floating pufferfish, then quickly squashed that dangerous thought by thinking instead about getting back before Isolde come looking.

‘Well, good luck with your secret thing, Maynard, but can you take a look at the robot? It doesn’t do any cleaning—just goes back and forth then stops.’

‘Give me a minute,’ he said, and in a whir of tools he removed the turret to reveal the complex workings.

‘I can’t find much obviously wrong,’ he said, poking here and there and making various parts of it spin and oscillate. ‘The capacitor is well charged, and all the locomotion and control paths work fine.’

Doncia watched with interest, noting the construction of it, how all the wires and tubes came from a main box in the centre, and how that main box had a smooth glass surface.

‘Professor Javer—your father—designed these things, you know?’ Maynard said.

‘Yes,’ said Doncia proudly. ‘Where is the rock, the anrenn?’

‘It’s sealed inside the turret, so when you take it off the rest is just an ordinary machine. We say without the anrenn it is unmotivated, which makes it safe to work with, and repair or modify. Look, there’s the problem, nothing more than a dirty mating surface. It happens quite often with these cleaners, since they are always kicking up so much dust.’

He cleaned the glass surface with a few drops of liquid from a little bottle, and a polishing cloth, and did the same to a similar surface inside the turret, which he then refitted.

‘That should do it,’ Maynard said, and tapped the red button. The robot performed the little test, spinning its head turret and dashing left and right. It waved its slender antennae slowly, using them to feel out its surroundings, then began to sweep the floor which, with all the dust from the rocks, really seemed to need it.

‘Tell it to follow me, please,’ Doncia asked.

‘Can’t do it,’ said Maynard. ‘Only Grandfather and Isolde have the commander anrenn. You’ll have to tow it back on the cart.’

‘Stupid thing!’ Doncia said, then she remembered her manners.

‘Oh, your pardon Maynard, Sir, I don’t mean any disrespect. Thank you ever so much for fixing it.’ She chased after it and smacked its red button. ‘Now I need to get it back to the muster room.’ She gave him a hopeful smile.

‘I’ll steady the trolley,’ he said.

‘Thank you,’ said Doncia. They got the robot back onto the trolley, and began pulling and pushing it back toward the front wing. They made quick progress and Doncia was glad again for his help.

Half way back along the passageway Maynard stopped pushing.

‘What’s wrong?’ Doncia asked. ‘Why have you stopped?’

Maynard was staring through an archway, across an empty room, and through the window at the bronze statues of the porpoises, leaping motionless over their pool in the courtyard.

‘I was just thinking,’ Maynard said, ‘about what you said, that the floating box cannot hear how high it is. I thought you were nuts; how can it hear height? But then I thought of the porpoises, and how they use echoes to help catch fish and know where they are going in the sea.’

‘I just thought,’ Doncia said, ‘your box can float, but it crashes back down—it’s like it doesn’t know how high it is. Can’t it listen to hear how high it is?’ She’d been thinking about her pocketwatch, and how she used it, but she didn’t want to tell him that.

‘I think you might be just as brilliant as your father!’ Maynard said. ‘Doncia, can you manage the robot from here?’

‘Yes,’ she said, disappointed to lose his help, but pleased to have been compared to her father. Maynard sped away back along the corridor.

Doncia smiled broadly. She was so happy that towing the robot along seemed much easier.