As the twists of the passageway became ever tighter Septimus knew they must be nearing the center—then suddenly they were there. Shocked, Septimus saw Marcellus staring at the blackened archway that was once the entrance to the Great Chamber of Alchemie. But now the archway led nowhere—it was blocked by a thick slab of heat-damaged metal, curled away at the bottom like a half-opened tin can. Marcellus crouched down to inspect it. “The barricade has blown,” he said.

“It’s done a pretty good job, all the same,” said Marcia.

“Possibly. I need a closer look.” Marcellus disliked the use of Magyk in the Great Chamber and the areas nearby—he was convinced it disrupted the fine balance of Alchemical reactions. But now a little bit of Magyk seemed nothing compared to the devastation surrounding them. “Perhaps, Marcia, you would care to use your FlashLight?”

Marcia switched it on and a guffaw escaped from Septimus.

“What?” asked Marcia irritably.

“You. Marcellus. Me. . . .”

Marcia realized that all three of them were covered with soot from head to toe. “Great,” she muttered.

For once Marcellus didn’t care what his robes looked like. He ran his sooty sleeve over his face, leaving behind a black streak across his eyes like a mask.

Marcia touched Marcellus on the arm. “I’ll do a Remove, shall I?” she offered gently. “The barricade is far too heavy for us to shift any other way.”

“Yes. Thank you, Marcia.”

Marcellus and Septimus stepped back and watched Marcia Throw a purple flash of Magyk across the metal slab. She waited a moment for the glimmering cloud to settle and then beckoned the barricade away from the archway.

The slab of metal began to shift and a sudden niggle of worry attacked Marcellus—there was something he must be careful about. But what?

“Septimus,” he said. “Get out of the way. Take cover.”

Septimus heard the warning in Marcellus’s voice and slipped into the entrance of the Labyrinth. He peered out to see what was happening. Marcia was concentrating hard, unaware that Marcellus was now anxiously hopping around.

“Marcia!” said Marcellus. “Marcia. Can you do a protection thing?”

“Huh?”

“You need to do some kind of shield thingy.”

Marcia shot Marcellus an angry look. What was he doing? Didn’t he realize he was disturbing her concentration? If he carried on twittering like that he’d be lucky if he didn’t get the barricade dropped on his stupid shoes. “Thingy?” she snapped.

“Spell. I don’t know. Whatever you call it.”

“I’m doing this now,” Marcia said. “I can’t be doing something else as well. Be quiet and let me concentrate, Marcellus.”

Marcellus gritted his teeth. The slab was shifting and he could see the gap between the stone of the arch and the metal widening: in a moment the barricade would be out. He knew that this was the dangerous part. But why?

Suddenly the barricade was floating in midair and Marcia was conducting it across the space in front of the arch like a seasoned builder directing a heavy weight swinging on the end of a chain. Marcellus breathed out in relief: nothing had happened. “It’s all right, Septimus, you can come out now,” he said.

The thick slab of black metal, still smooth and bright on the inside, was slowly shepherded by Marcia across to the opposite wall and lowered to the ground. It left behind a dark space, beyond which lay whatever was left of the Great Chamber of Alchemie.

Marcellus gulped. “I’ll go in first,” he said.

“We’ll go in together,” said Marcia.

Marcellus nodded. Sometimes he liked Marcia. He raised his candle up and saw something in front of him glimmering. There was someone there, deep in the dark, holding a candle—looking at him. Who was it? Who was in the Great Chamber of Alchemie, waiting for him?

The hairs on the back of Marcellus’s neck stood up as he saw a dark and desperate-looking creature, with eyes staring so wide that the whites glittered in the candlelight. Bravely, Marcellus took a step forward, then another and—“Ouch!” he gasped.

Marcia put out her hand. “Thought so,” she said. “Glass.”

“Glass?” Marcellus ran his hand over the smooth yet wavy surface.

“Yes. A second seal of glass. I’ll get rid of that too.”

Suddenly Marcellus understood. “Stop!” he yelled.

Marcia leaped back.

“Sand,” said Marcellus.

“Sand?”