“Don’t be silly, Marcia,” she muttered. “You Felt it. You know you did.”

Marcia decided to check out the other two arches even though she knew that they were both bricked up. She shone her FlashLight across the central arch and gave it a tentative shove, remembering something she had once read about Alchemists’ Mortar. It was solid and—eurgh—still greasily sooty. Marcia wiped her hand on her handkerchief and moved on to the right-hand arch, shining her FlashLight into the darkness.

To her shock, Marcia saw that there was a gaping hole in the brickwork below the archway. She felt a huge feeling of relief—so this was where they were. Marcellus had opened up an old tunnel and presumably they had got lost. She hurried into the opening and suddenly the ground disappeared below her right pointy python. Marcia toppled forward. A cold gust of air came up to meet her as she teetered, arms flailing, on the brink. She grabbed hold of the wall beside her but it gave way, sending bricks hurtling down into the dark. Some seconds later she heard the clang as they hit something far below.

Panic shot through Marcia. She knew that she was balanced on the edge of a precipice.

17

FALLING

A sudden boom woke Septimus from an uncomfortable doze. He jumped up.

Marcellus groaned. “What was what?”

“Something landed on the roof!”

“You were dreaming, Apprentice,” said Marcellus.

“No. No, I’m sure I heard—”

Booooooomboomboombooooooom!

Suddenly the chamber reverberated to a hail of objects slamming onto its roof, ending with a huge whuuump of something heavy and soft, which sent shudders through to their feet. Marcellus and Septimus felt the chamber tilt, and then the brief but sickening sensation of free fall.

What Marcellus and Septimus did not know was the moving chamber had become lodged just above the top of the exit door where, over the centuries, a fat helictite had formed so that it obstructed its path. The falling objects had provided enough force for the chamber to snap the helictite and continue on its way. Fast.

Luckily it was only a ten-foot drop.

There was a bone-jarring crump. Marcellus and Septimus picked themselves up from the floor. They looked at each other in the darkness but saw nothing but the total absence of light that had oppressed them for almost fifteen hours.

“It’s not tilting anymore,” said Septimus. “That must be a good sign.”

“Let us hope so,” muttered Marcellus.

“I’m going to try again and see if the door will open,” said Septimus.

“It won’t,” Marcellus said flatly. “There’s no orange arrow. That means no power.”

“We may as well try,” said Septimus. “Unless there’s anything else exciting you had in mind?”

“There is no need to get tetchy, Apprentice.”

“I am not tetchy.”

“No. Of course not. Well, you take one side and I’ll take the other.”

They had already done this countless times before the chamber fell for the second time—desperately pressing their palms over the cold, smooth surface of the chamber with absolutely no response—but now they began again. Septimus took one side of the chamber and Marcellus the other. Suddenly the darkness took on a faint orange hue. Marcellus gasped.

“The arrow—it flickered! Quick, quick, Apprentice. The door’s on your side. We may have a chance. Press it now! Now!”

The problem was that without being able to see the telltale worn patch—the dim orange glow did not give out much light—Septimus could not know whether his hand was in the right place or not. Marcellus joined him and frantically they pushed their palms onto the glasslike surface in increasingly wildly improbable places, desperately seeking the spot that might—just might if they were lucky—open the door. And all the time the orange arrow flickered, reminding Septimus of the distress lights on the Wizard Tower.

“It’s going! It’s fading!” Marcellus sounded desperate as his hands slapped frantically against the wall.

Septimus knew they were never going to find the right spot by panicking. “Stop,” he said. “I want to find it a different way.”

“I told you, Apprentice, Magyk does not work in here.”

“But my mind still works,” said Septimus. “Marcellus, please. Stop and be quiet a moment. Let me . . . let me Find it.”

The orange arrow was fading away and Marcellus knew they were getting nowhere. He let his hands drop to his sides. “Very well, Apprentice. Over to you.”