Three small arches led from the Alchemic Quay. Septimus took a rushlight from one of the holders. "This way," he whispered. "Better get a move on. It's a bit of a trek from the Quay, because the only way to get into the Chamber from here is through the Labyrinth."

"Labyrinth!" exclaimed Jenna. "But ... do you know the way, Sep?"

"Shh!" whispered Septimus. "You don't need to know the way through a Labyrinth, Jen. It takes you there. You just follow where it leads you and you will find what you look for. We go through the left archway."

"So ... where do the other ones go?"

"Oh, they'll drop you down into the Great Pitte of Fyre," said Septimus nonchalantly.

"Oh. Fine."

"It'll be all right, Jen." Jenna did not look convinced.

Septimus beckoned to everyone to come closer. Silently they gathered around, a little overawed by the strange, crypt-like feel of the UnderFlow Pool and the flickering, unearthly blue light reflected from the lapis lazuli.

"Let's get going," said Septimus in a low voice. "We've got to keep quiet and stay together. There are other tunnels that run into this one and we don't want anyone to hear us and come looking. Hang on to that panther, Snorri. Don't let it growl, whatever you do. If anyone sees or hears us, we've had it. Got that?"

They all nodded. Ullr's green eyes flashed and Snorri stroked him, saying, "Kalmm, Ullr. Kalmm."

They followed Septimus through the archway and set off in single file with the NightUllr padding behind them. His great soft paws were silent as they crept through the narrow opening, but there were muted gasps of amazement as they entered the Labyrinth. In front of them, the flames from Septimus's rushlight lit up great flashes of blue and gold. The Labyrinth was lined from top to bottom in finely jointed lapis lazuli interspersed with strips of gold.

Septimus set a fast pace and they followed behind him, walking upon the most brilliant hues of blue shot through with flashes of gold and deep green. The Labyrinth first took them outward, and then after many turns, Jenna was sure they had begun to walk toward the center. The deep blue of the lapis became almost hypnotic, and Jenna found herself feeling sleepy as she unfocused her eyes and gazed at the smooth blue walls. Every now and then she was woken from her almost trancelike state by the interruption of a dark archway, which signaled an entrance from a tunnel. Here Septimus would slow his pace and listen for other footsteps but they were lucky; it was by now the dead of night and even Alchemie scribes had to sleep sometimes.

Like a small and faithful flock of sheep, Jenna, Nicko, Snorri and the NightUllr followed Septimus through the blue haze of light, walking the long, slow curves, doubling back on themselves and walking the same curves in reverse, until everyone, particularly Nicko, felt dizzy and longed to be out in an open space once more. And then, just as Nicko was despairing of seeing anything but blue walls ever again in his entire life, they reached the center of the Labyrinth, and stepped into the Great Chamber of Alchemie and Physik.

"Whoa-ho." Nicko whistled. "That is amazing."

Septimus no longer thought of the Great Chamber as anything like amazing. Every day he had sat in his Siege of the Rose next to Marcellus, whose Siege of the Sunne was at the head of the table set in the middle of the Chamber. Every day had been the same, just another working day for Septimus.

But to Jenna, Nicko and Snorri, the Great Chamber was dazzling. They felt almost blinded by the glinting of the multitude of shiny golden surfaces that caught the light from the dancing flames of Septimus's rushlight. But it was not the small pieces of gold that had caught their attention, it was the two massive chunks of the stuff set into the wall opposite the entrance to the Labyrinth - the Great Doors of Time.

"That's where I came into this place," Septimus whispered, glancing around the Chamber, half afraid that there might be a scribe lurking in the shadows. On each side of the Doors, standing in a lapis lazuli-lined alcove, was a life-size statue holding a razor-sharp sword.

Jenna stared at the Doors. She thought about what Septimus had told her lay behind them, the True Glass of Time, and she felt a terrible longing to be home in her own Time, with everything back as it should be: Septimus in the WizardTower with Marcia, Nicko working down at Jannit Maarten's boatyard. She would be back in her own Palace, free of the living Etheldredda, at least, and once again the Palace would be a friendly place, home to Silas and Sarah pottering about and occasionally getting lost.

"We have to get the Keye, Sep," she said. "We have to."

Nicko, ever practical, was eyeing the Doors with a boat-builder's eye. "I'm sure we could get them open somehow," he said. "Those hinges look a bit weak to me."

"They're not just ordinary doors, Nik," said Septimus. "They're Locked with Marcellus's Keye." Nicko was not convinced. He took his screwdriver out of his pocket and poked it into one of the hinges. The statues raised their swords and pointed them at Nicko.

"Whoa there," protested Nicko. "No need to get excited."

Ullr growled. "Shh, Ullr." Snorri stroked Ullr's neck and pulled him close to her, but the NightUllr's orange-tipped tail was fluffed out like that of an irritated house cat, and his hackles were raised.

It is strange how voices carry through a Labyrinth. They find their way along the passageways and appear in the center as clear and bright as if the speaker was standing beside you, particularly if the voice has the penetrating quality of a dentist's drill. Which is why everyone in the Great Chamber of Alchemie and Physik suddenly jumped with fright as the shrill tones of Queen Etheldredda entered the Chamber. "I care not to hear thy troubles, Marcellus. I shall have the Potion now. I have tarried long enough. This night did show me not to suffer fools, and I will not suffer thy foolishness a moment longer. Oh, for how long does this lamentable Labyrinth wind its tedious way?"

"For as long as it must, Mother."

The sound of Marcellus's exasperated voice spurred Septimus into action. "They're coming," he whispered. "Quick - into the fume cupboard. We'll have to wait until Etheldredda's gone."

Septimus opened the door of a large cupboard in the wall and blew out his rushlight. With only the glow from his Dragon Ring to light their way, everyone squeezed into the foul-smelling cupboard and Septimus pulled the door closed.

"Oh, rats," muttered Septimus, his ring lighting up what Jenna had assumed was a coil of black rope on the shelf at the back of the cupboard, "I forgot the snake was in here."

"Snake?" whispered Jenna.

"Yeah. It's okay, it's not all that poisonous."

"So how poisonous would 'not all that poisonous' be then, Sep?" asked Nicko, who was fighting a longing to open the door and just get out of there.

But no one heard Septimus's reply. Queen Etheldredda made sure of that.