Septimus waited for Marcia at the foot of the steps. “I think opening the Great Chamber of Alchemie and Physik might be a bit more complicated than that. And anyway, it hasn’t got a door.”

“All the better, then,” said Marcia. “I shall just declare it open and then I’ll shoot off. I shall be busy this evening.”

Septimus had the distinct impression that Marcia was expecting to cut some kind of ceremonial ribbon and then go home. But he knew better than to say anything. He set off quickly.

Marcia hurried across the Courtyard, trying to keep up with her Apprentice. As she hurried through the Great Arch, her Wizard Induction vow came back to her. Marcia sighed. She felt as though she were on her way to betray the Castle.

5

THE GREAT CHAMBER OF ALCHEMIE

The atmosphere was strained but polite as Marcellus Pye ushered Marcia and Septimus into his house on Snake Slipway.

“Welcome, Marcia. Welcome, Septimus, or should I say, Apprentice,” he said, smiling.

Septimus heard a tut from Marcia but to his relief she said nothing more. He lugged his backpack inside and dumped it on the floor with a crash. Both Marcia and Marcellus winced. Septimus saw his black-and-red-velvet Alchemie Apprentice cloak with its heavy gold clasp hanging ready in the hallway. He gave Marcia an anxious glance and saw that luckily Marcia did not recognize what it was.

“Let’s get going, shall we?” said Marcia impatiently.

“Get going?” asked Marcellus.

“Yes, Marcellus. To the Great Chamber of Alchemie. Isn’t that the idea?”

Marcellus looked shocked. “What—are you coming too?” he said.

“Naturally I am coming too, as you put it. Surely you didn’t think I would allow you to open up that place on your own?”

That was precisely what Marcellus had thought. He fought down panic. The Chamber of Fyre was below the Great Chamber of Alchemie and the Fyre was beginning to come to life. What if Marcia noticed the warmth that had begun to spread upward—wouldn’t she think it was odd? Marcellus told himself sternly that Marcia would not know what was odd and what wasn’t. He must not give her any cause for suspicion.

“Er, no. Of course not, Marcia. Absolutely not,” he said. And then he added tentatively, “You . . . you’re not planning on staying there, are you?”

“I have much better things to do, thank you,” snapped Marcia, remembering Milo’s note.

“Then of course you must come,” he said, as if magnanimously inviting Marcia to a party where she had been left off the invitation list.

“Yes,” said Marcia stonily. “I must.”

It was not easy to get to the Great Chamber of Alchemie, which was one of the most successfully concealed Alchemie Chambers in the world. Septimus and Beetle had once thought they had stumbled across the empty iced-up Great Chamber of Alchemie in the Ice Tunnels, but it was the decoy Chamber, installed in ancient times when traveling bands of marauders would target Alchemie Chambers for their gold. Enough gold objects would be left in the easily found decoy Chamber to satisfy the thieves, and the true Great Chamber would remain undiscovered.

After the Great Alchemie Disaster the hidden entrances to the Great Chamber were erased from Castle maps, so that they were eventually forgotten—except by Marcellus. But he was not about to divulge any of them to Marcia. As far as she knew, the only entrance was through a murky, smelly underground stream called the UnderFlow, and that was the way they would be going. The old Alchemie Boat had long ago rotted away, so Marcellus went next door to Rupert Gringe’s boathouse to hire a paddleboat.

Rupert was doing winter maintenance on his fleet of brightly painted paddleboats, which he hired out in the summer for fun trips along the Moat. Rupert was used to his eccentric next-door neighbor, but Marcellus’s request for a paddleboat, just as the Moat was beginning to ice up, floored him.

“You what?” he said, running his hand through his short, spiky red hair.

“I wish to hire a boat,” Marcellus repeated.

“What, now?” Rupert looked at Marcellus as though he were crazy.

“Yes. Right now, in fact.”

“But there’s ice out there.”

“Ice can be broken,” said Marcellus.

“It will cost you. I’ve got them all laid up now and I’ll have to winterize it again.”

“Very well.” Marcellus handed Rupert a very heavy gold coin.

Rupert looked at it and whistled through his teeth. “Blimey. Don’t have change for a triple crown. Sorry.”

“Keep it,” said Marcellus. “Just give me the boat.”