‘Aye, aye, sir.’

A few minutes later, the top-eye view in the globe revealed the surface of a sea within Drowned Wednesday, or a large lake. It was illuminated by a pinkish glow from the stomach roof high above, a glow Doctor Scamandros suggested was from the reaction of specks of Nothing with particles of the House, both of them eaten by Wednesday and caked onto her stomach lining.

‘Very dangerous,’ the sorcerer added, staring into the globe with fascination and dread. ‘Too much Nothing. If enough of it managed to unfix from the House particles and it became concentrated . . .’

‘Can we look for anything like a . . . well, anything big enough to be Feverfew’s worldlet?’ asked Arthur.

‘Rotate top-eye.’

The view in the crystal globe slowly moved around. At first it revealed only more monotonous, greenlit sea. Then there was a sudden flare of colour, bright enough to make Arthur blink.

There, a few miles away, was a shining dome rising out of the sea. A dome easily a thousand yards high and five or six miles in diameter, its rainbow sides shimmering with all the colours of the spectrum, like a giant soap bubble in the sun.

‘Immaterial Walls,’ commented Doctor Scamandros. ‘Very fine work, particularly on such a scale.’

‘That’s it,’ said Arthur. ‘It has to be. Now we need to find the entrance.’

‘Keep us at top-eye depth,’ instructed Longtayle. ‘We’ll do a circumnavigation, see if anything is visible. Snout-eye view.’

‘Probably be guards somewhere,’ said Suzy. ‘Or traps or the like. I mean, it is a pirate’s secret worldlet, ain’t it? If it were mine, I’d have guards and traps all over the place.’

‘Let’s hope not,’ said Arthur. ‘I mean, it is inside a giant whale, to start with, and Feverfew comes and goes by sorcery. It’s not as if they’d be expecting anyone to come in except the salvage slaves they sent out.’

‘Speaking of salvage slaves, I think that might be one there,’ said Longtayle. He pointed at a dim shape in the globe. ‘Not moving, though . . .’

Arthur leaned forward to get a better look. There was a human-shaped figure standing still on the stomach floor. As the submersible edged closer and its lights shone through the murky water, the figure became clearer. It was humanoid, rather than human. About seven feet tall, it had a human face with a beard and long hair, but its muscular bare arms glittered with green scales, and there was webbing between its fingers.

‘A Nisser,’ said Longtayle. ‘But petrified or frozen.’

‘What’s a Nisser?’ asked Arthur. The creature had been stilled in the act of reaching out for something, his webbed fingers ready to grab. He looked angry, his mouth open, showing many small sharp teeth.

‘Drowned Wednesday’s guards,’ said Longtayle. ‘Like the Commissionaires in the Lower House, or the Winged Servants of the Night in the Middle House. She ate them up.’

‘This one made it through,’ said Suzy. ‘Do you reckon we can wake him up, Doc?’

Scamandros put his quartz-lensed glasses on his forehead and peered at the globe. Then he shook his head.

‘He is tightly wound with a very sophisticated binding. I could unpick it, but not easily, and not underwater.’

‘Feverfew, I guess,’ said Arthur. ‘Hey! There’s another one, closer in.’

‘Port ten and slow ahead,’ instructed Longtayle.

The submersible gently turned and progressed closer to the rainbow-hued dome. Its light spread through the water now, dimming the white beams from the submersible’s front. In this ripple of colours, there was a dark silhouette. Another Nisser, this time frozen in the instant she had raised a trident for a killing thrust.

‘And another two,’ said Suzy. ‘Over there, right near the dome.’

She pointed at two tiny dark specks on the very edge of the snout-eye view. But when the Balaena drew closer, the two figures were not Nisser. They were Denizens, or rather the skeletons of long-drowned Denizens, dressed in rags and manacled at the ankles, a long, algae-covered chain stretching between them. Both clutched long rakes, the metal heads blooming with rusty flakes and curls.

Arthur was both horrified and fascinated to see that the Denizen’s bones were, as far as he could tell in the rainbow light, a dull golden colour.

‘Interesting,’ said Scamandros. ‘Denizens don’t usually decompose. I suppose this water must have stomach acids in it, like a mortal creature. Or it may be the result of Nothing contamination. I presume this pair must be enslaved flotsam rakers.’

Longtayle’s tail twitched. Arthur saw him look around the bridge, as if he might see signs of the corrosive sea already affecting the submersible.

‘That brings up an important matter,’ said Longtayle. ‘We must presume that the waters of this stomach are dangerous to the Balaena, so we cannot linger. I’m afraid we can only give you twelve hours, Lord Arthur. After that, we must attempt to leave the Leviathan.’

‘Is that twelve hours from when we find the way in?’ asked Suzy.

‘Twelve hours from now,’ said Longtayle.

Arthur nodded. He was still staring into the globe. There was something about the rainbow-hued wall just beyond the two skeletons. If he looked from the corner of his eye, he could see something that might be an arched doorway. But when he looked straight on, all he could see were swirls of colour, shifting and changing like oil in a puddle on the road.

‘Can anyone else see a door?’ he asked. ‘An archway, about eight feet high, just behind the left-hand skeleton?’

‘Nope,’ said Suzy.

‘No,’ said Longtayle.

Doctor Scamandros put his glasses on his forehead and looked closely where Arthur was pointing.

‘Mmmm, an archway. . . yes. . . yes, there is a two-way membrane through the Immaterial Wall. Very cleverly concealed. How did you spot it, Arthur?’

‘I was just looking,’ replied the boy. ‘But I can only see it out of the corner of my eye.’

‘A useful talent,’ said Doctor Scamandros. ‘Particularly for you, Lord Arthur. I should make a habit of looking out of the corner of your eye. You never know what might be there, unseen.’

‘If there is a doorway there,’ said Longtayle, ‘we’d best drop you off, Lord Arthur, and find somewhere to hide the Balaena.’

‘How will you know when to come and get us?’ asked Arthur.

Longtayle reached into his pocket and pulled out a small wooden box. Opening it, he showed Arthur a tiny green bottle packed in cotton wool.

‘This is a one-shot bottle,’ he said. ‘Paired to one here. It can send only a single word, which is already in it. All you have to do is pull out the cork and the message will go. As soon as we get it, we’ll come in for the rendezvous. Also, if anything happens to us and we can’t pick you up, the bottle will crumble to dust.’

‘Thanks,’ said Arthur. He turned his head to look sideways at the globe. The arched door was still there, about fifteen feet away. ‘Doctor Scamandros, this membrane thing in the Immaterial Wall — does that mean there’ll be air on the other side of the door?’

‘Probably. But not certainly.’

‘Have you got one of those clothespeg charms? You know, the ‘thousand and one breaths’ thing?’

‘I fear not, Arthur. Has the one Wednesday’s Dawn provided already failed?’

Arthur nodded and looked at the globe again.

‘It’s not far,’ said Suzy, correctly guessing that Arthur was worried about the distance underwater from the submersible to the door. ‘Bound to be air on the other side, even if we have to go up for it.’

‘Providing the water doesn’t dissolve us or burn us,’ said Arthur. He knew he was procrastinating, but he couldn’t help it. ‘And what if there’s a trap, like you were talking about before?’

‘Nah, you’re right,’ said Suzy. ‘Why bother, if you’re inside a whale?’

‘I hope you’re right,’ said Arthur. ‘Or I’m right. Okay, I guess we’d better get going.’

He picked up his rat nose and rat tail and started to put them on.

‘Are these things waterproof, by the way?’

‘Hmm?’ asked Doctor Scamandros, who was looking at the dome wall again.

‘Are they waterproof?’

‘Of course! I am a marine sorcerer, remember. Every charm and spell I have made since I signed on to the Moth has been highly resolute in the face of dissolution by the universal solvent!’

‘So they’re not exactly waterproof,’ said Suzy, while Arthur was still trying to work out what Scamandros had said. ‘How long will they stand up to a good soaking?’

A ship tattoo that was sailing across Scamandros’s face suddenly hit a rock and sank, though it did manage to launch its boats, which rowed away towards his chin.

‘It is very unusual to demand complete waterproofing,’ sniffed Scamandros. ‘I would expect these charms to withstand an immersion of four or five hours in normal seawater. Less in this noxious brew. It is the paper, of course, that is most at risk, though woollen yarn, once sodden, is also —’ ‘Thank you, Doctor,’ interrupted Arthur. ‘If we’re going, let’s go.’

Better to get this part over with, he thought. At least I’ll be out of this metal coffin …

‘There is an escape chamber towards the stern,’ said Longtayle. ‘You’ll have to go out one at a time.’

‘I’ll go first!’ said Suzy.

‘No, you won’t,’ said Arthur. ‘I’ll go first this time. It’s my responsibility.’

Suzy shrugged and tipped her hat, allowing Arthur to go ahead of her to the rear bulkhead door.

The submersible was longer than Arthur had thought. Having only seen from the conning tower to the bridge, he was surprised by how much corridor they had to go along, and how many doors they went through. But they encountered only one other Rat, waiting for them at a door marked DORSAL ESCAPE AFT. Arthur was surprised to see it was Gunner’s Mate First Watkingle.

‘Did you volunteer?’

Watkingle grinned, which looked rather fearsome on a four-foot-tall rat.

‘Always volunteer, that’s my motto, sir,’ he said. ‘None of this ‘don’t get into trouble’ namby-pamby stuff. Why, when I think of the things I might ’ave missed —’

‘Thank you, Watkingle,’ said Longtayle quellingly. ‘Show Lord Arthur and Miss Suzy to the escape chamber.’

‘Aye, aye,’ said Watkingle. He turned his head slightly so Longtayle couldn’t see and winked at Arthur before undogging the door and opening it. The chamber beyond was like a very small shower stall with a hatch in the ceiling instead of a showerhead. On the side of the hatch were two handles. One was painted yellow and one painted red. A brass plaque on the hatch said in inch-high letters PULL YELLOW. WAIT FOR IMMERSION TO THE RED LINE. PULL RED.

‘The procedure for emergency evacuation from the craft is simple and straightforward,’ lectured Watkingle in a singsong voice. ‘First, you will enter the chamber and close the door behind you. It will automatically latch and cannot be reopened from inside. Second, grasp the yellow handle with one paw and pull. This will open a valve and water will enter the chamber. Third, when the water level reaches the red line painted around the wall of the chamber, take a normal breath. Do not take many breaths or take a deep breath. Then, grasp the red handle with one paw and pull. This will open the exit hatch. Fourth, kick off from the floor and swim out. Understood?’

Arthur looked into the chamber. The red line was about four inches from the top. He would have to crouch a bit and keep his head back to have his face out of the water for that last breath. The hatch was big enough for him to fit through without a problem.

‘Okay,’ he said. ‘Get in. Pull yellow handle. Wait till the water reaches the red line. Take a breath. Pull red handle. Swim out.’

‘That’s it, sir,’ said Watkingle.

‘I’ll swim to the door and go through,’ Arthur told Suzy. ‘I’ll meet you on the other side.’

‘This looks like fun,’ said Suzy. She rubbed her hands together and added, ‘Sure I can’t go first?’

‘No,’ said Arthur. ‘As in ‘no, you can’t go first.’ I guess we’d better put on our disguises now.’

He tied on the rat nose and fixed the tail. When he looked around, Suzy was near his feet, already a rat. Arthur presumed he appeared to be a rat as well.

‘I’m ready,’ he said.

Suzy squeaked something back at him.

‘What?’ asked Arthur. Then the realization hit him: They looked and sounded like rats to each other as well as to everyone else.

Arthur lifted off his rat mask and unhitched his tail.

‘We won’t be able to talk to each other when we’re wearing these,’ he said. ‘So once we’re inside, follow me.’

Suzy squeaked, then was herself again, holding her rat nose.

‘Whatever you say,’ she said.

Before Arthur could make sure she really meant it, she’d turned back into a rat.

‘I mean it,’ said Arthur. ‘Follow . . . as in, stay behind me.’

He slipped the rat nose back on and refastened his tail, then stepped into the escape chamber. The door shut behind him and he heard a heavy bolt or latch sliding across.

Arthur rubbed his suddenly sweaty hands against his breeches, checked that the Atlas and Wednesday’s invitation were secure in his Immaterial Boot, and reached up to pull the yellow handle.