Simon nodded uneasily. He didn’t like being the one with the Darke knowledge, but he knew that was the way it would always be. And if he could use it for good, then at least there was some purpose in what he had once done. “You said there was a hole in the box?” he asked Marcia.

Marcia stared at Simon, the awful truth beginning to dawn on her. Of course. She had been too focused on the Heap twins to think it through properly.

Simon saw Marcia’s expression. He coughed apologetically. “I believe that the Two-Faced Ring has . . .” He glanced at Marcia.

“Migrated,” Marcia finished for him.

“Surely not,” said Alther. “It takes thousands of years for that to happen.”

Marcia put her head in her hands. “It was on its way a few weeks ago. Septimus and I had to put it back in the Bound Box.”

Simon looked shocked. If he had been ExtraOrdinary Wizard he would not have left the ring alone for one second after that.

“But that still doesn’t explain how Edmond and Ernold were able to get the ring,” said Beetle. “I mean, they had to break the Seal to get it. And really I don’t think they were up to that. They were just a couple of bumbling old . . .” Beetle trailed off, aware that they were Septimus’s uncles.

“Fools,” supplied Septimus, who shared Beetle’s opinion.

“Exactly,” said Simon. “The more foolish the better.”

Marcia looked at Simon. “Simon. I think you know something about this ring that we don’t.”

Simon nodded. “When I was with, um, the ring’s previous owner, he told me that the ring was very near what he called Reversion. I think he was quite scared of that happening. He knew that all it needed was something big for that to become possible.”

“Like a Darke Domaine?” asked Marcia.

“Yes. Exactly. And I think that last night, the ring had an opportunity to enter the first stage of Reversion.”

Marcia swore.

Septimus looked shocked.

“Sorry,” said Marcia. “I shouldn’t have said that.”

“I would have done if you hadn’t,” said Alther.

Beetle looked confused. “What is a Reversion, exactly?” he asked.

Marcia indicated to Simon to speak.

Simon leaned forward. The candlelight lit up his green eyes and his fingers fiddled nervously with a stray thread from his tunic, twisting it around as he spoke, self-consciously aware that all eyes were upon him. “It is a return to a former state of existence. In the case of the Two-Faced Ring, its former existence was two Darke Warrior Wizards: Shamandrigger Saarn and Dramindonnor Naarn.”

The candle on the desk guttered and spat: there were some names that were not to be spoken in the Pyramid Library and these were two of them. Silence fell. Beetle got goose bumps.

Quietly, Simon continued. “A Reversion is not straightforward. It must go through stages. The first would be to find something unresisting to InHabit, which—not surprisingly—appear to be my uncles. I assume they were InHabited last night when they were on Seal Watch. And of course, there were two of them. I suspect that the fact that they were twins actually made them a target.”

“So it wasn’t Ernold and Edmund who stole the Two-Faced Ring,” Septimus said quietly. “It was the ring that stole them.”

“Yes,” said Simon. He looked upset. “Poor Ed and Ern . . . a Consuming Habitation. They do not deserve that.”

Everyone was silent. A Consuming Habitation was a terrible fate.

But Septimus was still puzzled. “So why did the Ring Wizards wait in the Seal lobby all night?” he asked.

“They would need to get control of the InHabitation,” said Marcia. “They would have to access the Wizard Tower password from the Heaps in order to get out.”

Simon looked at Marcia. “That’s true,” he said. “But actually, I suspect they were waiting for you. They’d want to get rid of you as soon as they could. It’s lucky you got the Shield right—and so fast.”

Marcia nodded.

“I wonder why the other Wizards on Seal Watch didn’t notice them?” Beetle said. “You’d have thought two Darke Wizards hanging around in that tiny lobby there would have been Seen.”

Simon gave a rueful laugh. “Nope. Not being Seen by a few very Ordinary Wizards is easy for them.”

Marcia got to her feet. “Right,” she said. “It’s not good but at least now we know what we are up against. First we get Edmund and Ernold. Then we do the Committal to get the Ring Wizards back in the ring. And then we DeNature the ring.”