While Septimus was walking into the unknown with Syrah, far below the sea Wolf Boy and Lucy were deep in their own unknown. Breathing in stale air that smelled of leather, the cold of the sea numbing their feet, they sat behind Miarr as the Red Tube purred through the depths. Each stared out of a thick glass window, seeing a strange combination of their wide-eyed, pale reflections and the darkness of the sea beyond. Far above them - so far that it made them feel a weird inverse vertigo - they could see the Light moving slowly across the surface of the water, like the moon sailing across a starless sky.

"Mr. Miarr," said Lucy. "Mr. Miarr."

Miarr's neat head appeared around the edge of his tall seat, his yellow eyes glinting in the red glow.

"Yes, Lucy Gringe?" His oddly crackly voice gave Lucy goose bumps.

"Why is your voice funny?" asked Lucy. "It's weird."

Miarr pointed to a circlet of wire around his neck. "This makes it so. It is what the pilot must wear. It is to make it easy to speak to many people in the Tube after a rescue. If it is necessary to be heard in a storm and to inform ships of the danger of the Isles, it will also carry sound to the outside. My voice is not strong, but with this it is." Miarr's head disappeared back behind his seat.

Now that she knew the reason Miarr sounded so odd, Lucy relaxed a little.

"Mr. Miarr?"

"Yes, Lucy Gringe?" There was a smile in Miarr's voice as he spoke.

"Why are we so far down? It's creepy."

"I wish to follow the Light without being seen. These marauders are bad people."

"I know," said Lucy. "But couldn't we go just a little nearer to the surface? They wouldn't notice us, surely."

"It is safer here," crackled Miarr.

Lucy gazed out, watching the beam of light from the Red Tube cut through the indigo water, illuminating forests of seaweed waving like tentacles, waiting to drag people into their clutches. Lucy shuddered. She had had enough of tentacles to last her a very long time. Suddenly something with a big, triangular, spotty head and two huge white eyes shot out of the weeds, swam up to the window and head-butted it hard. The Red Tube shook.

Lucy screamed.

"What is that?" Wolf Boy gasped.

"It is a cowfish," said Miarr. "They taste horrible."

The cowfish's googly eyes peered in wistfully.

"Oh, it's revolting." Lucy shuddered. "I bet tons of them live in that weed."

But it was the sight of real tentacles - thick, white ones with big pink suckers - emerging from the forest of weeds and curling toward the Red Tube that finally did it for Lucy.

"Aaaaaaaaaaaaaaaaaaaargh!" she screamed.

"Up!" Miarr's voice crackled, and they shot above the tentacles and the weeds into brighter waters. The Red Tube continued on its way, its pilot skillfully shadowing the Marauder, keeping his course some twenty feet below his Light.

He reasoned - correctly - that none of the crew would be looking too closely into the brilliance that followed them.

Surrounded now by clear green water and more familiar-looking fish, Lucy and Wolf Boy settled back into their seats and began to enjoy the sensation of flying below the water, as Wolf Boy put it, dodging between jagged-topped rocks that stretched toward the sun, stopping just below the surface. Miarr offered them a ration box containing - to Lucy's delight - a bag of chocolate raisins among the packets of dried fish and bottles of stale water. The chocolate raisins tasted somewhat fishy, but Lucy didn't care - chocolate was chocolate. She changed her mind, however, when she realized that the raisins were tiny fish heads.

Above the water, not so far away, Beetle was having little success with the familiar-looking fish. He and Jenna were sitting on a large rocky plateau by some very deep water - so deep that the usual pale green of the sea was a rich, dark blue. They sat watching the sea lapping against the rocks, peering down, seeing the seaweed on the rocks moving dreamily with the currents below. Every now and then they caught sight of fish swimming languidly in the depths, haughtily ignoring Beetle's offering. There were obviously a lot nicer things to eat down there than hook-buried-in-fish-head sandwich, Jenna said.

Beetle was disappointed. After his successes from his fishing rock, he had begun to see himself as an expert fisherman, but he now realized there was probably more to it than he thought. He wound in the fishing line.

"Perhaps we should get back to Sep and see how Spit Fyre is," he said. Jenna was quick to agree. She did not find fishing the most fascinating of occupations.

They walked across the rocky plateau, dropped down onto a stone-covered beach and picked their way across the shingle to the next outcrop of rocks. The tide was falling, revealing a long line of rocks, which stretched out to sea in a gentle curve, as though a giant had carelessly thrown down a string of massive black pearls. The line ended with a tall pillar-like rock that Jenna recognized as the one she had seen from their beach and had called the Pinnacle.

"Look, Beetle," she said. "Those rocks are like stepping stones. We could run along them all the way to the Pinnacle. Maybe we could even climb it and wave to Sep. That would be fun."

It wasn't exactly Beetle's idea of fun, but he didn't mind - if Jenna wanted to do it then he was happy to do it too. Jenna clambered down onto the first rock.

"This is great!" She laughed. "Come on, Beetle. See you there!"

Beetle watched Jenna set off, leaping from rock to rock, her bare feet landing surely on the slippery, seaweed-covered rocks. Less sure of himself, he started after her, stepping from rock to rock more carefully. By the time he reached the foot of the Pinnacle, Jenna was already at the top.

"Come on up, Beetle," she said. "It's really easy. Look, there are steps." There were indeed footholds cut into the rock - and a huge, rusty iron ring hammered into its side. Beetle climbed up the footholds and joined Jenna on the top. She was right, he thought, it was fun. Not quite as much fun as a double-whiz turn in the Ice Tunnels, but it came a very close second. He loved sitting way above the water, feeling the cool breeze in his hair, listening to the cry of the gulls and the swish-swash of the gentle waves below - and he especially loved sitting there with Jenna.

"Look," said Jenna, "there's our bay, but I can't see Sep anywhere."

"He's probably with Spit Fyre," said Beetle.

"Mm, I hope Spit Fyre's okay," said Jenna. "He did smell a bit disgusting this morning, didn't he? I mean, more disgusting than usual."

"Yeah," said Beetle. "But I didn't say anything. You know how touchy Sep gets about stuff like that."

"I know. It is lovely here, isn't it? When Spit Fyre is better we must bring Sep up here. It's amazing." Jenna gazed about, taking it all in. She was surprised at how narrow the island was. There was no more than a rock-strewn spit of land separating what she thought of as their bay from the coast on the other side of the island. She looked up at the one and only hill, which rose behind them. It too was strewn with rocks and was topped with a small grove of twisted, wind-stunted trees.

"Yeah, it is pretty special," said Beetle. They sat for a while, listening to the occasional cry of gulls and watching the sparkling sea, until suddenly Beetle said,

"There's a boat!"

Jenna jumped up. "Where?"

Beetle carefully got to his feet for a better look. There was not a lot of room on top of the Pinnacle. He shaded his eyes from the sun, which seemed extra bright when he looked at the boat.

"Over there," he said, pointing to a small fishing boat with red sails that had just come into view at the northern tip of the island.

"It's so bright," said Jenna, screwing up her eyes. "I can hardly look at it."

"Don't look at it," said Beetle suddenly. "It's too bright. I think...oh, how weird...I think they're towing a great big lamp!"

In the gentle breezes of the early afternoon, the Marauder was making slow progress toward her destination. Skipper Fry had sailed north of the island for a safer approach that avoided some notorious rocks, but the wind had dropped and it had taken much longer than he had expected. But now their destination was in sight.

"Jakey!" he yelled. "Keep a lookout. We're gettin' near the Lurkers!" The Lurkers were a string of jagged rocks scattered around the Pinnacle and lying just below the surface of the water.

Jakey was lying on the bowsprit, his feet dangling, peering down into the clear green sea. He was as far as he could get from the weird Light bobbing along behind them, and as far away as possible from his father and the Crowes, who felt even more menacing hidden behind their dark eyeglasses. No one had bothered to give Jakey any glasses, so he had spent the whole trip looking away from the Light with his eyes half-closed. He stared into the water, amazed at how clear it was, how he could see all the way to the seabed. There was not much to see, just flat sand, the occasional school of darting fish and - oh, what was that? Jakey let out a shout.

"Port or starboard?" yelled the skipper, assuming Jakey had seen a rock.

"Neither - oh, it's huge!"

"Where, you idiot -  where is it? " Skipper Fry fought to keep the panic from his voice.

Jakey watched a long, dark red shape come up from the depths. He had never ever seen a fish of that size - or that shape. The shape traveled smoothly under the boat toward the Light, and Jakey looked away. "It's gone!" he yelled. "I think it were a whale!"

"Idiot boy!" shouted Skipper Fry. "There's no whales 'round here."

Suddenly a yell came from Thin Crowe.

"What?" Skipper Fry, so near to his goal, was twitchy.

"There's some more bloomin' kids!"

"Where?"

"On the Pinnacle, Skip. Where you wanna put the Light."

"I know perfectly well where I want to put the Light, thank you, Mr. Crowe,"

Skipper Fry growled. "And I shall be putting it there very soon, kids or no kids."

"No kids is best," said Thin Crowe. "Yer want me ter remove 'em?"

"Lurker!" yelled Jakey.

Skipper Fry yanked on the tiller. "Where?" he shouted. "Port or starboard, boy?"

"Starboard," yelled Jakey.

Skipper Fry shoved the tiller away from him and the Marauder sailed past the jagged rock lurking below.

Jakey Fry looked up at the Pinnacle. They were getting closer. He thought it looked like Lucy on top, though he didn't see how it could be. But if it was Lucy, he hoped she got out of the way pretty quick. In fact, he hoped whoever it was got out of the way pretty quick.

With carefully engineered shouts of "Lurker, port!" and "Lurker, starboard!" Jakey Fry made sure the Marauder sailed out of the line of sight of the Pinnacle in the hope that Lucy Gringe - if it was her - had time to disappear.

In the excitement of nearly reaching their destination, Skipper Fry had forgotten something that all sailors know - sound travels loud and clear across water. Beetle and Jenna had heard every word from the Marauder, and they were not about to wait around to be "removed." They clambered down the Pinnacle and quickly made their way back across the stepping-stone rocks to the shore. Once on the rocks they ran, dodging for cover, toward a sweep of sand dunes below the wooded hill. By the time the Marauder came back into view the Pinnacle was once again deserted.

They threw themselves into the soft sand of the dunes and caught their breath.

"They can't see us here," Beetle puffed.

"No," said Jenna. "I wonder what they're doing?"

"Nothing good, that's for sure."

"That boat coming here," said Jenna, "it's horrible. It feels like...like..." She searched for the words.

"Like we've been invaded," Beetle supplied.

"Exactly. I wish they'd go away."

Beetle did too.

They watched the Marauder's approach. The boat was a dark, fat shape against the sparkling blue water. Its two triangular foresails billowed gently, its huge mainsail was out at right angles and its little staysail stuck out at the stern on a spar like a stubby tail. Behind it followed a great ball of Light, which competed with the afternoon sun - and won.

The Marauder finally made it to the Pinnacle, which stood out like a dark finger, taller than ever against the retreating tide. Jenna and Beetle watched a hefty figure clamber onto the landing platform and secure the boat to the iron ring. Then the Marauder swung around behind the rock so that they could see no more than the bowsprit and foresails jutting out from one side and the brilliance of the Light on the other.

For the next hour, Jenna and Beetle watched, through half-closed eyes, a bizarre operation from behind their sand dune. They saw a ball of brilliant light being laboriously winched up the Pinnacle until finally, secured by a web of ropes, it balanced precariously on the flat top.

"What are they doing?" said Jenna.

"I think they're wrecking," said Beetle.

"Wrecking - you mean like they used to do on Wild Rocks in the old days?"

"Yep," said Beetle, who like all Castle children had grown up with tales of the terrifying rocky coast beyond the Forest and the wild people there who lived by luring ships to their doom. "But the really strange thing is, they're using what looks like an ancient Sphere of Light. Where could they possibly have gotten that?"

"The lighthouse," said Jenna. "Remember how we couldn't see the Light this morning? They've stolen it from the lighthouse."

"Of course," said Beetle. "Wow, that lighthouse must be incredibly old. This is such a weird place."

"And getting weirder all the time," said Jenna. "Look at that." She pointed out to sea, where, to the right of the Pinnacle, a long red pipe with a bend at the top was rising from the water. Beetle and Jenna watched as the pipe swiveled around until it was pointing at the Pinnacle and stopped. It then stayed motionless. The only movement was from the white tops of tiny waves breaking over a red rock below the pipe.

"That's a Looking Tube," said Beetle. "We've got - I mean, they've got - one like that in the Manuscriptorium. It goes down into the UnStable Spell room so that we - they - can keep an eye on what's going on."

"So there's someone watching from under the sea?" said Jenna.

"Looks like it," said Beetle. "Like you said, it's getting weirder all the time."