S omeone," Marcia told Catchpole, "has defaced my door."
Catchpole jumped up guiltily, his sparse sandy hair standing up in surprise. Marcia had caught him taking a quick nap in the Old Spells cupboard. "Oh," he said.
"If this is your idea of a joke I don't think it is very funny," said Marcia icily.
Catchpole balanced on one leg like an embarrassed heron. He wasn't sure what Marcia was talking about but it sounded like trouble - again. "Oh, dear," he said.
"Well, is it?"
"Is it what?"
"Is it your idea of a joke? I know your penchant for drawing on doors."
The penny dropped. "Oh, no. It wasn't me, I promise. Absolutely not. Honestly - it wasn't."
Marcia sighed. She believed him. The bizarre scribbles were far too complicated for Catchpole to have done. "Well, go get a bucket and a scrubbing brush. I want them cleaned off. I'm off to see Sarah Heap and I expect a nice clean door by the time I return. Got that?"
"Got that, Madam Marcia. Will do." Reprieved, Catchpole shot off to find a bucket and a scrubbing brush.
"No!" Jenna gasped. "It's disappearing! Stop. Stop!" In front of them the map was vanishing.
"Quick, tell it to stop," said Nicko.
"Stop!" yelled Jenna.
"No - no, I mean write on it. Quick, Jen, before it all goes."
Jenna picked up the piece of chalk and scrawled: STOP! DO NOT ERASE.
Catchpole screamed and dropped the bucket of hot soapy water on his foot. Huge, looping letters were writing themselves across the door as he watched. It was worse than when he had started - what would Marcia say? Catchpole picked up the scrubbing brush and got to work with a vengeance, but even as he scrubbed, more words appeared in the very spot he had just cleaned. Suddenly Catchpole understood - this was a test. Marcia had set it so that he could prove himself worthy of being reinstated as a sub-Wizard. Catchpole was determined not to fail. As more and more words came into view telling him STOP! THIS IS AN URGENT MESSAGE! Catchpole sped up, catching each one with his scrubbing brush as soon as it appeared, splashing water everywhere. Soon the landing outside Marcia's rooms was a large, chalky puddle.
"More chalk!" yelled Jenna. "Quick!"
Snorri handed her a stub of chalk. "It's the last one," she said.
Jenna stopped, her hand poised above the door. She could not risk wasting this precious last piece of chalk. They watched MARCIA, WE ARE HERE! disappear from the door, followed by the rest of the precious map until nothing remained of Jenna's messages. "It's not going to work," she said miserably. "The door just gets rid of it."
Everyone fell silent, a feeling of despair hanging in the air. Suddenly Septimus said, "It did work. But someone is washing it off."
"Who would do that?" asked Nicko.
"Marcia wouldn't," said Jenna, "or any of the Wizards. They'd know it was important."
"So who would be so stupid?" said Nicko.
Septimus knew exactly who. "Catchpole," he said.
"Catchpole?"
"Yep. It has to be. No one else in the Tower would dream of doing that. Jen, give me the chalk. I know what to write."