Septimus was puzzled. “But no one has ever told me anything about the Fyre,” he said.

“They do not speak of it,” said Marcellus. “But if they ever do, I would like you to understand that it is not the terrible thing they say it is.”

“Right.”

“But . . . there is one little thing.”

“Yes?” said Septimus warily.

“Promise me that you will tell no one what you see today.” Marcellus glanced around as though he expected to find Marcia lurking in a corner. “Not even Marcia.”

“I can’t promise that,” Septimus said regretfully. “Not now that I am going back to Marcia. Anyway, Marcia asked you to start the Fyre, didn’t she, so she knows already.”

“Marcia thinks the Fyre we are lighting is in the Great Chamber of Alchemie. She does not know that the true Fyre is in the place that all ExtraOrdinary Wizards fear and have promised to keep Sealed forevermore—the Chamber of Fyre. If she knew that she would close it down, just as Julius Pike once did.”

“I don’t think Marcia would close it down, because she doesn’t know anything about it.”

“Of course she knows about it,” said Marcellus. “She is the ExtraOrdinary Wizard.”

“But before I was coming here I asked her about the Fyre and she said she didn’t know a thing. Nothing.”

“There are many things Apprentices are not told,” said Marcellus.

Septimus was not convinced. He knew when Marcia was deliberately not telling him things—she had a certain “don’t go there” warning look in her eyes. But when they had discussed the Fyre, Marcia’s expression had been one of bemusement. He remembered her saying, “There is something about this Fyre stuff that we just don’t know anymore. I wish I knew what it was . . .”

“Apprentice, let me explain,” said Marcellus. “After the Great Alchemie Disaster, the ExtraOrdinary Wizard, Julius Pike—who was once my dear friend—told me that he would make sure that all future ExtraOrdinary Wizards would never allow the Fyre Chamber to be UnSealed. Never again would the Fyre Cauldron be used. The only reason Marcia has agreed to the Fyre is because she thinks it is the one in the Great Chamber of Alchemie. And I know that, like any other ExtraOrdinary Wizard, Marcia would never let the Chamber of Fyre be opened. All I ask you is to keep it secret for”—Marcellus did some quick calculations—“another month? After that I will reveal it to Marcia, I promise.”

“But why in a month—why not tell Marcia now?”

“It will not be ready until then. Alchemical Fyre is delicate in its early stages of Life and takes time to reach maturity. But once the Fyre is ready and Marcia sees that it has been burning safely for some time, then I have a chance to prove to her that all is not as she has been told. Do you understand?”

“I suppose so. . . .” Septimus understood, but it did not make keeping the secret feel any better.

Marcellus was uneasy; it felt decidedly risky having Septimus go back to Marcia at such a delicate time. “That, Apprentice, is why I am so sorry you are leaving me now. Before it all begins. Perhaps, when you see the Fyre, you will reconsider your decision to leave.”

“It’s not really my decision,” said Septimus.

“Indeed, no. While you are Marcia’s Apprentice it is not your decision. It is hers. But if you were to decide to become the Castle’s first Alchemie Apprentice then that would be different.” Marcellus left the offer hanging in the air.

“Sometimes,” said Septimus, staring at his reflection in the dark waters of the UnderFlow, “I wish there were two of me. I wish I could be in the Wizard Tower and here at the same time.”

Marcellus smiled. “Even the greatest Magyk cannot make that happen,” he said.

“Not for longer than seven seconds,” said Septimus.

Marcellus looked impressed that it could happen at all.

Septimus thought for a while. “Okay,” he said.

There were three arches leading off from the Alchemie Quay, each one lit by a Fyre Globe. Marcellus headed for the right-hand archway. Inside the archway, he turned to Septimus apologetically.

“I know you do not like building work, Apprentice, but I assure you this is the last you will have to do.” Marcellus opened the old carpetbag in which every day he brought their lunch, and to Septimus’s surprise, from underneath the neatly wrapped sandwiches he took out a hammer and heavy chisel, which he handed to Septimus.

“Thanks,” said Septimus ruefully.