It took more than the weedy Catchpole's help to lift out the chest. It needed the combined efforts of five Ordinary Wizards—without Catchpole, who suddenly felt dizzy—to drag the chest onto the spiral stairs.

At the top of the Tower Marcia, Septimus and the five Wizards heaved the chest and dragged it along the landing. The great purple door to Marcia's rooms swung open, and everyone pushed and pulled the small but amazingly heavy chest inside. Marcia stood up with a groan and rubbed her back. “Are you sure this thing isn't just full of bricks?” she said. “What could it possibly have in it to make it so heavy? ”

“Gold. It's lined with really thick slabs of the stuff,” said Septimus.

“What on earth for?” asked Marcia indignantly.

“Because it's the purest, most perfect metal. And Physik is all about that too, sort of trying to reach perfection with ourselves...” Septimus trailed off, noticing Marcia's exasperated expression. It was not lost on the Ordinary Wizards either, who quickly scuttled away.

Marcia sighed. She looked down at the blackened old chest with its scraped gold corners and unbroken golden bands, and she just knew that it was going to be trouble. Not to mention the fact that it was making horrible dents in her best Chinese carpet. “It's all very well, Septimus,” she said somewhat grumpily, “but how on earth do you intend to open this thing?”

“Easy,” said Septimus. He knelt beside the chest and took the Keye from around his neck. Marcia watched as he pressed it into its mirror image on the front of the chest, and slowly the lid silently opened.

Septimus looked inside and smiled. Everything was as he remembered, neatly laid out, clean and tidy. Lines of gleaming gold instruments lay in a tray; bottles of tinctures and mixes, remedies and fusions lay just as he had left them. And, at the bottom of the chest was what Septimus was looking for: his carefully written formula for the antidote to the Sickenesse.

“Here it is,” he said, triumphantly pulling out a ragged piece of much-folded vellum.

“Look.” Septimus handed it to Marcia, who put her spectacles on. The hours of perusing Jillie Djinn's prediction tables and calculations had done her eyesight no good at all, and she peered at the fine brown-ink scrawl that covered the vellum. Her face brightened; at least she recognized what it was: an example of late Etheldredda/early Esmeralda variant script with the typical reverse scrawl used by the Physicians of those days.

“Right, Septimus,” said Marcia briskly, glad at last to be able to take charge. “Get yourself down to the Manuscriptorium and have the Ancient Script Scribe write you an immediate translation— immediate, mind. No messing about. There's no time to lose. Off you go. Well, go on.”

Septimus shook his head. “But I don't need to do that—I wrote this myself.”

Marcia felt very odd. She had to go and sit down.

Some hours later, Septimus was carefully drawing up a colloid of silver with his pipette and dropping it into a large flask. Marcia, feeling rather unnecessary, sat watching her Apprentice finding his way around the old Physik Chest with an ease that amazed her.

Despite Septimus's long tangled hair, which she really must get him to do something about, and the fact that he was definitely a little taller and thinner, she found it hard to believe that he had really been away for nearly six months of his life, while only two days had passed at the Castle. And something else was different about Septimus too. He was more assured and—this was what Marcia found really strange—now he knew and believed things that she did not. That took a bit of getting used to.

“Do I add the valerian to this or add this to the valerian? What do you think?”

Septimus's voice broke into Marcia's thoughts.

“You're the expert, Septimus,” said Marcia, trying to get used to her new role. “But as a general rule I would say add light to dark.”

“Okay.” Septimus added the greenish oil to the contents of his flask. “Now, could you pass me the balance, please?” he asked. Getting into her role of lab assistant, Marcia handed Septimus a small set of gold scales complete with tiny gold weights.

She watched him pick up the smallest weight with a long-nosed pair of tweezers and place it on the balance. Then, taking out a tiny, round-bowled gold spoon, Septimus measured out a fine blue powder and poured it onto the other side of the scales until the two sides were delicately balanced, and then something caught his eye. He looked at the spoon more closely and frowned.

“What's wrong?” asked Marcia.

Septimus passed her the spoon. He pointed his blue-stained finger to some marks underneath the handle.

Marcia fished out her spectacles from her pocket and peered at the scratches on the spoon. “Sep ... tim ... us,” she read slowly.

“I remember writing that,” said Septimus. “It was the day after I ... arrived. I wrote my name everywhere for a while. It was like writing messages forward to our own Time.”

Marcia folded up her spectacles and dabbed at her eyes with her purple silk handkerchief. “That powder stings,” she said. “You should put the lid back on.”

Several hours later, when the mixture had cooled, Septimus went back to complete the serum. He removed the large crystal that had formed, crushed it in a mortar and pestle and returned the powdered crystal to the flask. He put a stopper in the flask, shook the mixture for thirteen seconds until it became clear and poured it into a tall clear glass medicine bottle. Now Septimus lit a candle. Then he took his diving rod from the Physik chest, dipped it into the mixture, turned it seven times and held it up to the candle flame. It looked good. Septimus placed a clean piece of silk over the open top and pushed a cork down onto it, creating a tight seal.

“It's finished!” he called up the stairs. Marcia hurried down.

“Now for the final test,” said Septimus, a little nervously. Marcia watched her Apprentice pick up the bottle and hold it up to the light of the little arched window, turning it so that it caught a ray of sunlight. The sunlight struck the glass, traveled through the liquid and emerged as a blindingly blue streak of light. “It works—it works!” Septimus shouted.

“No more than I would expect.” Marcia smiled. “Now, get your cloak, Septimus, we have to get this to where it's needed. There is no time to lose.”

As Marcia and her Apprentice quickly crossed the Wizard Tower courtyard, the dragon kennel shook as Spit Fyre hurled himself at the door. Septimus ran up to the door and said, “I'll be back soon, Spit Fyre. Really, I will. Then you can come out. I promise. See you later, Spit Fyre!”

“Jenna will have to UnDo the Seek,” Marcia told him. “He'll be a complete pest until then. He won't leave you alone.”

“I know,” said Septimus, clutching the bottle of Antidote close and running to catch up as Marcia took the side gate out into a small alley. They were on their way to the Infirmary. Knowing Septimus's dislike of heights, Marcia ignored the shortcut along the Castle walls and instead took the winding streets below. Septimus thought that he had never been so happy as he was now, except perhaps when he had returned to the Wizard Tower from the Manuscriptorium the previous day and the writing across the floor had said, WELCOME BACK TO YOUR TIME, APPRENTICE. WE HAVE MISSED YOU. That had been a good moment, a very good moment. Septimus loved the fact that once again he was wearing the green robes of the ExtraOrdinary Apprentice, rather than the black and red robes of an Alchemie Apprentice, and it was his friends that called out and said hello, with no weird accents and strange words that you always had to think twice about.

Soon they reached the North Gate.

“Afternoon, your ExtraOrdinariness,” said Gringe, blocking their path.

“Oh. Good afternoon, Gringe,” said Marcia, a little curtly.

“You going anywhere nice?” asked Gringe as Marcia tried to squeeze around him and get onto the drawbridge.

“No. Would you mind getting out of the way, please, Gringe?”

“Oh. Sorry, Your ExtraOrdinariness. Of course.” Gringe squeezed himself against the gatehouse wall to allow Marcia and Septimus to pass. “Oh, hello,” said Gringe, noticing Septimus. “You gave your poor dad a couple of sleepless nights, you did.”

Suddenly Septimus remembered. Dad ... Gringe ... Etheldredda's portrait.

"Gringe—you have to go down to the Palace right now, and you have to tell Dad to put that picture back exactly where you found it. Then he's got to ReSeal the room.