Septimus was in his room, packing his bag. His small, round room at the top of the Wizard Tower was neat and orderly, a result of its occupant's ten years of training in the Young Army. Dreadful and dangerous as those years had been for Septimus, now that the Young Army was disbanded and he was reunited with his family, he had begun to stop despising everything that he had learned as a boy soldier. He was no longer wildly untidy just because he could be; after a brief period when it had resembled the Municipal Rubbish Dump, his room was now neat and ordered. The room bore other traces of his previous life too: its dark-blue curving walls and ceiling were covered with the constellations, accurately painted by Septimus, who had had to memorize them for his Young Army night exercises. And in his cupboard he always kept an emergency backpack, packed strictly in accordance with the Young Army regulations.

Septimus's emergency backpack contained:

compass (1)eyeglass (1)water bottle (1)bedroll (1)socks (3)mess tin (1)tinderbox (1)spare flints (2)kindling (moss, dried, bunch of)ex Young Army regulation pen knife (1)catapult (1)wire, length of (1)rope, length of (1)

To this Septimus was now busy adding a few things that reflected his new life as Apprentice to the ExtraOrdinary Wizard. They were:

Unseen Charm (1)Seeker's Charm (1)Fast Freeze Charm (1)Double Action Escape Pack (1)

Plus a few bits and pieces that he thought may come in useful:

The Little Book of Survival and Bushcraft by Ram Seary (1)Wiz Bix, everlasting, packet of (1)Mint Blasts, tubes of (3)

There wasn't room for much else, but there was one last thing that Septimus wanted to take. It broke all the rules because it was both unnecessary and heavy, but Septimus didn't care. Down the side of the backpack Septimus stuffed the smooth iridescent green rock that Jenna had given him when he had first known her. With some difficulty, Septimus buckled up the backpack and put it on. It was heavier than he had expected.

"Is that you, Septimus?" Marcia called out as he came down the stairs and headed for the front door. He jumped in surprise.

"Yes," he replied warily.

Marcia was kneeling on the floor beside the ShadowSafe. In front of her was a huge piece of paper with an extremely complicated diagram on it, which she was examining closely. For a brief, horrible moment, Septimus caught a glimpse of a large murky figure leaning over her, also peering at the paperbut when Septimus looked more closely the Shadow faded from view. But he knew it was still there, hovering behind Marcia, silently staring at the plans for its own demise. Septimus put down his heavy backpack; he felt bad about leaving Marcia alone with her dark companion.

"What's a flange?" asked Marcia.

"A what?"

"A flange. It says here attach piece Y to the long, upright D, taking care to align holes P and Q with the corresponding holes N and O in the left-hand flange. I can't see a wretched flange anywhere." Marcia rifled irritably through a large box of fixings that Professor Van Klampff had given her for the construction of the ShadowSafe.

"It's not in the box," said Septimus. "It's that bit that sticks out. Look, there " He ran his finger down a curved projecting rim that ran the length of the edge of the ShadowSafe. The Amalgam felt like glass to the touchsilky smooth and cold.

"Well, why didn't it say so," said Marcia grumpily as she slotted piece Ya long, curved triangular sectiononto the ShadowSafe, carefully aligning holes P and Q with holes N and O. Marcia dusted down her tunic with an air of satisfaction. "Thank you, Septimus, it's looking good, isn't it? Only one more piece to go down the side here, then the final Stopper and"Marcia twisted around, trying to catch sight of her Shadow"you will be gone, you pathetic creature."

Septimus looked at the ShadowSafe. Good was not the word he would have used to describe itweird, maybe, or just plain ugly was more like it. It rose from the floor, dominating the room with its shiny blackness and bizarre shape, which reminded Septimus of a gnarled hollow tree. The odd assortment of molded panels, which Professor Van Klampff had so carefully constructed, had come together to form a roughly conical enclosed space, open at the top, with a long narrow gap running from top to bottom through which Marcia and her Shadowfor a Shadow must Follow whether it wants to or notwould eventually squeeze. Then someone, probably one of the more senior Wizards (as Marcia felt it was a lot of responsibility for her young Apprentice), would place the last piece, the Stopper, in the hole in the top, and Marcia would walk out, free at last, leaving the Shadow trapped inside, like a lobster in a lobster pot. After that it was a simple job for the Bin Disposal Squad.

"Hang on, Septimus," said Marcia, suddenly remembering what she had said to him earlier, "what are you doing back here? I gave you the day off. You should be up at the Palace with your mother."

"I'm going to find Jenna," Septimus said, picking up his backpack and heaving it onto his shoulders. "Seeing as no one else will."

Marcia sighed. "Look, Septimus," she said patiently, "Jenna will be back soon, mark my words. You're just a little upset after your spider bite. It's perfectly normal."

"I am not upset," he said indignantly.

"Septimus," said Marcia, "I know you think I don't believe you"

"I know you don't believe me," said Septimus.

"but, just to put your mind at rest, I have done a Remote Search of the Farmlands across the river and there is a horse with two riders on its way to the North Gate. It is bound to be Jenna and Simon after their morning out. And I have sent Boris"

"Boris?" asked Septimus.

"Boris Catchpole. Moved in yesterday, he's a new sub-Wizarda bit old really to get started as a Wizard but he's very keen. He's part of our Second-Chance Scheme. He trained as a Tracker in the Army. Got as far as Deputy Hunter, believe it or not."

"Old Catchpole?"

"Yes, do you know him?"

"He's horrible!"

"He's not so bad. Well, apart from his breath, that is. That's pretty bad. I must have a word with him about it sometime. Anyway the past is the past. We should welcome him in. Well, we will be welcoming him next week with the traditional Wizard Warming Supper, and as Apprentice you will of course be there."

Septimus looked gloomy.

"All part of the job, Septimus," said Marcia briskly. She looked at her glum Apprentice standing by the door weighed down by his heavy backpack. His green eyes looked sad. His sister had chosen to go away on one of his few days off, and it was hard on the boy. Marcia knew that Septimus was very close to Jenna after their experiences together in the Marram Marshes.

"Look, Septimus, if you want to take your adventure bag or whatever it is you've got there and go outside the Castle to wait for Jenna to come back, that's fine. Off you go. It's a lovely day and you could walk up to the One Way Bridge and watch out for her."

"All right," he said doubtfully.

"I'll see you later then," said Marcia with a fond smile. "And don't forget to take Jenna straight back to the Palace. Why don't you stay the night? Then you can spend some time with Jenna and your parentsand come to think of it, you can make sure Jenna gets off to the Marram Marshes tomorrow. The boat has been ready for her at the Palace Quay for a week now, and I am really worried that she won't leave in time. Your mother does tend to leave everything to the last minute." Marcia sighed. "You know, I am sure when the Queen used to go for her MidSummer Visit she must have left earlier than this, although the funny thing is I can't ever remember her going. I mean, she must have gone on the royal barge, but I don't remember it and neither does Alther. And how did she get across the Marsh? Sometimes, Septimus, I worry about Jenna. There are so many things her mother would have told her about, and who can do that now? How will she ever know how to be Queen?"

"I suppose we all have to help her," said Septimus. "Which is what I'm trying to do."

"Yes, of course you are," said Marcia soothingly. "Now you go and have a nice day. Give Jenna my love when you see her, and tell her I hope she has a good MidSummer Visit."

Marcia made everything sound so normal that Septimus started to allow himself to believe that Jenna really was coming back. "Yes," he said, a little more brightly. "All right then. I'll do that. I'll see you tomorrow."

"Off you go," said Marcia as the huge purple door to the ExtraOrdinary Wizard's rooms threw itself open for the Apprentice.

'"Bye," replied Septimus. He stepped onto the silver spiral stairs and they began to move, quickly taking him out of sight. The purple door closed itself quietly, and Marcia did something she had never done before: she wandered upstairs and went, uninvited, into Septimus's room. She walked over to his window and waited for him to emerge from the Tower. Then she watched his progress across the Wizard Tower courtyard, a small figure in green carrying his heavy backpack, his unruly, pale, straw-colored hair making it easy to see him even from twenty-one floors up. As Septimus disappeared into the shadows of the Great Arch, Marcia walked away from the window and out of the room, gently closing the door behind her.

Septimus took the shortcut to the North Gate. The shortcut was a high path set into the Wall that surrounded the Castle. It was narrow and unfenced, and was somewhat alarming if you did not have a head for heights, which Septimus did not. On the right-hand side of the path was a sheer drop of about twenty feet onto roofs, into backyards or, in one terrifying stretch, a drop of fifty feet straight onto the Ramblings Road, which led to The Ramblings. The Ramblings was a huge warren of a building that formed the east wall of the Castle and sprawled for three miles along the river. It was a noisy, busy place filled with a maze of passages and rooms where many of the Castle inhabitants lived and worked, and it was where the Heaps had lived before their sudden move into the Palace.

On the left-hand side of the path were the thick stone battlements of the Wall. As he walked along the path, Septimus stared fixedly at the worn yellow stones of the ancient Walls and told himself not to look down.

Once Septimus had made the mistake of glancing to his right just as he was walking above the Ramblings Road. A feeling like an electric shock had run through him, starting at his feet and ending in his head, making him sway dangerously. He had had to sit down, then close his eyes and crawl to the nearest exit steps. But Septimus believed in conquering his fearswhich was what always took him up to the Wall, rather than through the longer, but much less scary, alleyways and sideslips to the North Gate.

Today, as Septimus hurried along the path, he paid little attention to the heighthe was too busy thinking about Jenna and planning what to do. Although he had begun to wonder whether Marcia was indeed right and Jenna was on her way back, something deep down told Septimus that Jenna was in trouble.

And if Jenna was in trouble, he was going to help herwhatever it took.