A small orange cat sauntered out of the tunnel that led to the Royal landing stage. "Ullr!" gasped Nicko.

"Shh," warned Septimus.

Nicko picked up Ullr. "Snorri?" he whispered into the tunnel. "Snorri?" But it was Jenna who came out of the darkness, not Snorri.

In the Great Chamber of Alchemie and Physik, Marcellus Pye was alone. He was sitting in his Siege of the Sunne at the head of the table, head in his hands. At the sound of approaching footsteps in the Labyrinth he panicked. He jumped up, ran into the fume cupboard and closed the door, trembling. He could not face his mother, not right now.

"What do you mean, she just fell in the water, Jen?" Nicko's whisper carried into the Great Chamber. "Didn't she try to get out?"

"No, she just went sort of plop and disappeared. It was weird. Like ... like she couldn't be bothered to do anything about it. It was as if she thought it didn't really matter."

"Well, it wouldn't, would it, if you thought you were going to live forever?" Septimus pointed out.

Inside the fume cupboard Marcellus heard every whispered word and the realization began to dawn on him that they were talking about his mother.

Jenna was still shaken from seeing her great-great (and then some) -grandmother drown. "But I didn't wish her dead. Really I didn't - "

Marcellus gasped and clutched at a shelf for support. Dead? Mama was dead?

"Aargh!" There was a sudden yell from inside the fume cupboard and the door crashed open. The cupboard's previous occupants leaped with shock as Marcellus Pye rushed out, clasping a long black snake just behind its head between his thumb and forefinger. The snake's mouth was open and its white fangs dripped venom down the front of Marcellus's black tunic. "Forsooth, 'tis a vicious brute," Marcellus gasped. He sped over to the bench where the phial of his Tincture had until recently been resident, pulled the top from a large glass jar, threw the snake in and slammed the top back on.

Then, carefully wiping the venom from his tunic - which had produced an interesting effect on the orange sauce - he surveyed his stunned audience. "Pray, Septimus," he said quickly, "do not run from Here."

Septimus sighed. So much for their ambush. Marcellus had ambushed them. Wearily, he pulled out his chair at the Siege of the Rose and made Jenna sit down. She looked pale and had red marks around her neck from the Aie-Aie's tail. Still feeling shaken, Jenna scooped up Ullr and hugged the cat close for comfort. Suspicious of Marcellus, Nicko hung back; but Septimus, as was his habit when he had nothing to do in the Chamber, perched on one of the scribes' stools and yawned. It would not be long before the working day in the Chamber of Alchemie and Physik started and the early-morning scribes began to arrive.

Marcellus caught Septimus's yawn. It had been a long and difficult night. He sat down in his great high-backed chair at the head of the table and regarded Jenna and Septimus with a thoughtful air. There was something he wanted to discuss.

Nicko hung back from the table. He was having none of this cozy conversation with the man he regarded as Septimus's kidnapper. It seemed to him that it would be easy to take Marcellus unawares. Nicko figured that with the muscles he had recently acquired working in the boatyard, he was a match for anyone, especially a lanky Alchemist who looked as if he had inhaled too many mercury fumes. The only thing that held Nicko back was Snorri. Where was she? What should he do? Nicko hovered, so enmeshed in his thoughts that he did not hear the offer that Marcellus Pye was making Septimus.

At the end of their conversation both Marcellus and Septimus were smiling. The decision made, Marcellus leaned back in his chair.

Nicko meanwhile had also made a decision. He would get the Keye. It was now or never. With skills learned from Rupert Gringe, he lunged at Marcellus from behind and grabbed him by the throat.

"Take the Keye, Sep - quick!" he yelled.

"Aargh!" Marcellus gurgled, half strangled as Nicko wrenched at the thick chain from which the Keye dangled.

"No, Nik!" shouted Septimus as Marcellus began to turn a nasty purple.

"We gotta do it now." Tug. "It's our last chance." Yank. "Come on, Sep, help me." Wrench. Marcellus's eyes started to bulge, and he began to resemble some of the pickled purple frogs on the top shelf of the fume cupboard.

"No, Nik!" Septimus pulled Nicko away, and Marcellus collapsed, gasping, back into his chair.

Nicko was furious. "What did you do that for?" he demanded. "You idiot!"

"He's just offered us the Keye, you dillop," said Septimus. "He's going to let us go - or he was."

Jenna poured Marcellus a glass of water from a jug on the table. He took it with a shaking hand and drank it down. "Thank you, Esmeral - er, Jenna. Prithee take some for yourself, for I do believe you have as much need as I do." Marcellus turned to Septimus. "Now, Apprentice, dost thou still wish to go through the Great Doors? Perchance thee might find less violent friends in thine own Time."

"I do still wish," said Septimus, "and I wish my friends to go with me."

"Very well, if thy Friends so wish it - though 'tis an Unknown Danger to go forward to a Time not your own. All who have gone have never Returned. Which is why these Doors are Guarded at all times." Marcellus got to his feet and regarded Septimus gravely. "So we are agreed?" he asked.

"Yes," replied Septimus.

"I trust thee," said Marcellus, "as I have never trusted any Person before. Not even my dearest Broda. My Life is in your hands, Apprentice."

Septimus nodded.

"What's going on, Sep?" Nicko hissed, who didn't like the sound of this.

"The Conjunction of the Seven Planets," Septimus told him.

"The what?"

"Marcellus can't make another Tincture - one that will work - until the same Conjunction of the Planets happens."

"So? Hard luck for Marcellus and all that, but what's it to do with us?"

"Well, it happens tomorrow."

"Good for them."

"It happens tomorrow - in our Time."

Nicko shrugged. He didn't see what the planets had to do with going home.

"I have promised to make the Tincture in our Time, Nik. Tomorrow at the time of the Conjunction. I can make it so that Marcellus can be young in our Time, too. I am sure I can.

"He's coming with us?" asked Nicko, shocked. "But he kidnapped you."

"No, he's not coming with us. He's there already, just really old and sick. I'm going to try and make him okay. Now, stop asking questions, Nik. Don't you want to go home?"

The truth was that Nicko wanted desperately to - but not without Snorri. He kept glancing at the entrance to the Great Chamber in the hope that she would suddenly rush in, pale hair flying, eyes shining, and he could tell her that they were all going home.

Marcellus took the Keye from around his neck, inspecting the misshapen links on the chain that Nicko had very nearly succeeded in breaking. He went over to the Doors and began to make preparations for their opening. The statues sheathed their swords and bowed their heads as Marcellus placed his Keye into its mirror-image indentation in the center of the Great Doors. And then, deep within the Doors, Septimus heard a sound that made the hairs on the back of his neck prickle - the rumble of the bar inside moving, a sound that he had last heard when the Great Doors had closed behind him one hundred and seventy days before.

Slowly, silently, the Great Doors of Time swung open, the gold flashing in the candlelight as they moved apart to reveal the dark surface of the Glass, which stood patiently waiting beneath them: Septimus had forgotten how deep the Glass looked, and as he gazed into its depths he felt as if he were standing on the edge of a precipice. A familiar feeling of vertigo swept up from his feet and made him sway.

"Fare thee well, Septimus," said Marcellus, "and thank you."

"Thank you, too, for all you taught me about Physik," replied Septimus.

"Now take thee this," said Marcellus, to Septimus's surprise, handing him the Keye. "It will open the Glass at the top of the lapis steps, which is where thee must Go Out. It is thine to keep, I shall make another for myself. I shall place thy Physik Chest sub rosa in the cloaks cupboard at the top of the steps to the WizardTower. Use it well, thou hast the makings of a great Physician."

"I will," Septimus promised. He took the Keye and placed it around his neck. It felt heavy and was still warm from Marcellus's touch. "But how," he asked, "shall I get the Tincture to you?"

"Fear not, I wouldst not ask thee to bring it through the Glass, for I know the horror thou hast of such a thing. Place the tincture, pray, in a gold Box marked with the Symbol of the Sunne and throw it into the Moat beside my House. I will find it."

"How will I know that you have found it?" Septimus asked.

"Thou shalt know by the presence of the Golden Arrow of Flyte, which I didst see upon my Ancient Person. I shall place it in the Box by return. Art thou a fisherman?"

"No," replied Septimus, puzzled.

"Methinks thou wilt become one," Marcellus chuckled. "The Golden Arrow of Flyte will be my thanks to you and will bring you great freedom."

"It already has," muttered Septimus, "until you took it."

Marcellus did not hear; he had turned his attention to Jenna.

"Fear not that my mother should continue to Haunt thee in thine own Time," he told her. "Although she hath drunk of my Tincture which, while incomplete, may give her Spirit some Substance, she shall not trouble thee. The ExtraOrdinary Wizard and I shall Entrance her into her portrait. Methinks I shall also hunt down the Aie-Aie, for did it not too drink of my Tincture? It truly is a most Poisonous Creature and doth carry a Pestilence in its bite, which Mama hath used to terrify all who displease her. So, Jenna, it is decided: I shall Entrance them both into the portrait and Seal them in a room that None shall find."

"But Dad Unsealed it," Jenna gasped.

Marcellus did not reply. Something in the Glass had caught his attention.

"Dad did what?" asked Septimus.

"He and Gringe Unsealed Etheldredda's portrait. You remember. It was hanging in the Long Walk - "

Marcellus's voice interrupted Jenna. With an unmistakable note of panic, he said, "Pray do not tarry, this Glass hath become Unstable. I can see cracks appearing deep within. It will not hold for long, I fear. Go you now - or never!"

Deep within the Glass Septimus saw what Marcellus had seen. Beyond long, lazy swirls of Time moving within it, fissures were materializing around the edges of the Glass. It was indeed now or never.

"We've got to go!" yelled Septimus. "Now!" He grabbed hold of Jenna with one hand and Nicko with the other and ran at the Glass.

At the very last moment, Nicko wrenched away. "I'm not going without Snorri," he said.

"Nik - you must come, you must," said Septimus desperately.

"The Glass will not wait," said Marcellus, urgently. "Begone, begone before it is too late."

"Go!" yelled Nicko. "I'll see you later. I promise!" With that, Nicko ran from the Great Chamber of Alchemic and Physik.

"No, Nicko. No!" Jenna yelled.

"Come on, Jen," said Septimus. "We've gotta go."

Jenna nodded and together, with a small orange cat, they stepped into the Glass and walked into the liquid cold of Time.