What puzzled Marcia was that although she and Alther had found nothing positive, they had found some strange absences. In many of the shelf indexes there were unexplained gaps, even complete empty pages. The Alchemie section was almost nonexistent apart from some very basic student primers, and the notes relating the Ice Tunnels went back no further than when they were Frozen after the Great Alchemie Disaster, which was very odd, Alther said, because they were as old as the Castle itself. It seemed to both Marcia and Alther that a large chunk of Castle history had been systematically removed. And Marcia was beginning to suspect that the lack of information about the Fyre and the Vents was linked. They must be, she thought, part of the same system and were therefore removed at the same time. But why?

“The funny thing is, Marcia,” Alther said as he wafted through the pages of yet another index, “you wouldn’t know things were missing unless you were looking for them.”

“Exactly,” Marcia agreed. “And if you didn’t know about them to start with, you wouldn’t be looking for them, would you?”

“If you ask me,” said Alther, “someone has spent a long time up here, systematically removing anything relating to Alchemie and ancient structures beneath the Castle. It must have been an ExtraOrdinary Wizard—no one else would have had the access. I wonder who it was?”

“More to the point, I wonder why,” said Marcia. She thumped a pile of pamphlets down and a cloud of dust Passed Through Alther. The ghost spluttered. “Careful, Marcia. I’m allergic to dust.”

Marcia laughed. “You can’t be, Alther. You’re a ghost.”

Alther looked a little offended. It was not polite to remind a ghost of their ghosthood. “Well, I am,” he said huffily. “Ever since that ghastly Drago Mills place.”

“It’s not totally ghastly,” said Marcia. “I got a very nice rug from the sale. Oh, hello!”

The little door to the Library had swung open and Septimus and Jenna came in.

“How lovely to see you both!” said Marcia. She looked at her Apprentice, who she had not seen for some weeks. “Oh, Septimus, you look so pale.”

Septimus fielded a barrage of questions about whether he was eating properly and did he ever get outside in the daylight, and then went to talk to Alther, leaving Jenna to ask Marcia’s advice about the Dragon Boat.

Ten minutes later, Septimus, Jenna and Marcia were out in the corridor, waiting for the stairs to change direction. They were on slow mode due to the arrival of the elderly parents of one of the Wizards, and Marcia was polite enough to wait until they had got off. Septimus watched the silver treads rise sedately upward; the shafts of sunlight coming in through the azure-blue glass of the stairwell window threw lazy, glimmering patterns onto the solid silver treads. He loved this time of day in the Wizard Tower; there was something Magykal about the evening sun when it came in low through the windows. Septimus took a deep breath and breathed in the scent of Magyk—sweet with a hint of sandalwood.

“Have you seen him acting suspiciously?” Marcia said suddenly.

“Huh?” said Septimus, heady with the Magyk.

“Marcellus. Have you noticed anything . . . strange?”

It was a difficult question for Septimus to answer: many things that Marcellus did could be thought of as strange—especially by Marcia. But Septimus did not like to tell tales. “No,” he said.

The stairs changed direction and Marcia hopped on. “I’ll look forward to seeing you back here tomorrow evening, Septimus.” She looked at her Apprentice critically as he stepped back to let Jenna get on before him. “It’s not good for you, being buried like a mole under the ground.”

Marcia was beginning to disappear from view. Jenna jumped on after her and made her way down a few steps until she was near enough to talk. “It really is all right, then?” she asked Marcia. “The Dragon House staying open?”

“Fresh air and some sunshine—just what the Dragon Boat needs,” Marcia said. “And Septimus too.”

The stairs were now approaching the fifteenth floor. Dandra Draa, the new Sick Bay Wizard—headhunted by Marcia for her skills in DisEnchantment—had just finished an emergency callout to a Wizard who had been convinced he had Enchanted himself by reading an ancient text. Dandra had diagnosed Papyrophobia and was now on her way up to see Marcia. She was waiting patiently for the stairs to change direction when she saw the distinctive purple pointy pythons appearing above her.

“Good afternoon, Madam Marcia,” said the Sick Bay Wizard. She waited politely for Marcia to rotate past.