A half-rat, half-human face was eerily illuminated in the yellow glow of Septimus's Dragon Ring.

Jenna suppressed a scream.

The body of Ephaniah Grebe was propped up in the far corner of the tree house, exactly where the Thing had left him for the more agile frame of the Toll-Man. Ephaniah's head lolled forward like a broken doll's, and his white robes looked like a pile of dirty sheets waiting to be washed. As soon as Jenna saw him, she knew he was UnInHabited - the difference between Ephaniah now and the last time she had seen him was obvious. This was Ephaniah - she felt no revulsion, no sense of overwhelming rat-ness and none of the feeling of pity and hopelessness that the InHabited Ephaniah had filled her with. And, she saw, his left little finger was ring-free. She rushed over to the rat-man and touched his hand. It felt cold.

"Oh, Sep, can you Hear...anything?" she whispered.

Septimus knew what Jenna was asking. He Listened for the Sound of Human Heartbeat. "I don't think so," he said, then he saw Jenna's expression and added hurriedly, "but I think that's because there's so much rat there. All I can Hear is Beetle's, which is slow and steady, and yours, which is really loud."

"Oh," said Jenna, surprised. "Sorry. What about yours?"

"You can never Hear your own," said Septimus. He thought for a moment. "We'll do it the old way," he said.

Septimus kneeled beside Ephaniah and took his emergency Physik tin from his pocket. The tin was crammed full of things that Jenna had no idea why he could possibly want. From it he selected a small, round mirror and held it close to Ephaniah's slightly open mouth from which two long, narrow teeth protruded. A light misting appeared on the glass. "Well, he's still breathing," said Septimus.

"Oh, Sep, that's wonderful." Gently, Jenna stroked the rat-man's soft nose, intrigued at the way the human features merged so well with the rat fur. As she stroked the fur, Ephaniah's eyes fluttered open for a brief moment. "He saw me," whispered Jenna. "His eyes smiled. He's okay. I know he is."

"It'll take a while to be sure about that," said Septimus, who knew enough Physik to know that nothing is certain. "But at least he's got a chance."

The tree house was surprisingly comfortable, if a little strange. It was completely lined with a coarse reddish fur, and once the door flap was closed no light entered at all. In the opposite corner from where Ephaniah lay, his head resting on a pillow that Jenna had made from the Toll-Man's blankets, there was a small stove set on a thick piece of slate. After several attempts to light it with Beetle's tinderbox, Jenna finally coaxed a large yellow flame from the big round burner. Septimus took the battered old pan that hung from a hook above the stove, climbed down the tree and scooped up some snow. With his pan piled high with snow, poised to climb back to safety, he stopped for a moment and listened. A bloodchilling ululating howl - the same one that they had heard the night before - pierced the air and Septimus felt the ground tremble beneath his feet.

Startled, he looked up and saw a long, dark shape moving along the path around the chasm. It was coming toward him - fast. With a sudden certainty Septimus knew what it was - and what had gone past them earlier hidden in the fog. He did not waste a moment; he dropped the pan and shot back up the rope ladder. As he threw himself into the tree house, the whole tree began to shake.

"Earthquake!" cried Jenna.

Septimus shook his head. "No," he said. "Foryx!"

Terrified and fascinated at the same time, Jenna peered out of the door flap. A phalanx of Foryx was hurtling through the snow, so fast that Jenna's only impression was a long, red streak of galloping fur and tusks as the Foryx thundered past on the path below the tree house.

"They're real!" said Jenna.

"A bit too real," said Septimus.

A few minutes later, pointing to the walls of the tree house, Jenna said, "You know what fur this is, don't you?"

"Foryx," said Septimus with a grimace.

Jenna smiled. "Which means, if you think about it, that we are already in a House of Foryx."

"Well, I wish Nik were here," said Septimus glumly.

"I know. So do I."

Jenna made Septimus go back for some snow. "We'll hear them if they're coming back," she said when Septimus had objected. "And make sure you get the snow from a clean patch. We don't want Foryx dribble for supper."

Septimus broke the record time for snow collection. While Jenna boiled up some witches' brew, Septimus sat next to Beetle and looked through his Physik tin with a feeling of anticipation. At last he was getting a chance to try out the Physik he had learned on a real patient. Beside him his unwitting patient dozed peacefully on the floor of the tree house, pale but breathing steadily. The thick yellow flame of the stove filled the tree house with a comforting glow and the warmth began to bring out the pungent smell of the Foryx skins. Septimus decided it was time Beetle woke up and drank some witches' brew. He took out a small phial labeled Sal Volatile and was about to waft it under his new patient's nose when Beetle suddenly opened his eyes. Foryx skin reek was as effective as any phial of Sal Volatile.

Beetle had a nasty gash behind his right ear and now that he was warming up it was beginning to throb painfully. "Ouch!" he protested as Septimus cleaned up the dried blood with some sphagnum moss dipped in antiseptic.

Jenna looked up as she was dropping three squares of toffee into the boiling water. "You're turning him purple, Sep." She laughed.

"Purple?" said Beetle. "Wotcha doing, Sep?"

"It's Gentian Violet," Septimus explained. "It will stop the cut from getting infected. But we need to keep the edges together. Wait, I've got something here." Septimus picked up a large needle.

"What's that for?" asked Beetle suspiciously.

"Oh, that? Well, when I was learning about Physik, Marcellus took me to watch a surgeon at work,"

said Septimus. "Someone came in with a deep cut and he sewed the edges together."

"He did what?" Jenna asked, wide-eyed.

"You're joking," said Beetle.

Septimus shook his head.

"Eurgh, Sep, that's disgusting," said Jenna. "You can't sew people up like...like bags of flour."

"Why not? It works."

"Well, you're not doing it to me," Beetle told him. "So you can put that needle away right now."

Septimus smiled, pleased that Beetle sounded like his old self. "I wasn't going to sew you up, Beetle,"

he said. "Your cut's not big enough and it's in an awkward place for stitches anyway. I was just looking for a bandage. Ah, here it is."

Beetle allowed Septimus to put a clean piece of moss over his cut and wrap a bandage around his head. He obediently drank all of the witches' brew that Jenna had made and was soon asleep on the Foryx skin floor.

"Marcellus would say that we ought to wake him every few hours to check that he's sleeping and not unconscious," said Septimus.

"But he won't be sleeping if we wake him, will he?" Jenna objected. "He'll just be grumpy and tired tomorrow."

"I know," said Septimus. "Anyway, I think he's fine. His breathing is good."

Jenna smiled. "You know," she said, "even though it was horrible, you being trapped in Marcellus's Time, you've come back really different - in a good way. You know stuff. Stuff that no one else does.

Not even Marcia."

"Yeah," said Septimus glumly. He was silent for a while and stirred his witches' brew, watching the toffee whiz around faster and faster. Then he said, "I'd be a better Physician than a Wizard."

"Don't be ridiculous," said Jenna. "You'll be a great Wizard. One of the best. You know you will."

"Marcia doesn't think so."

"She didn't say that."

"No. But I can tell she thinks it. She says I just mess around with stuff. It's true, really. I...I don't think I want to be a Wizard really, Jen."

Jenna nodded. "Sometimes I think I don't want to be Queen," she said. "It's horrible to feel you have to be something. At least you can decide not to be a Wizard if you don't want to be."

Septimus did not reply. He put his hand in his pocket and felt the Questing Stone. He didn't think there was going to be much chance of deciding anything anyway. "Jen," he said.

"What is it, Sep?" Jenna looked concerned.

"Oh...nothing." He couldn't say it.

Later, when night had fallen and Jenna and Beetle were sleeping, the NightUllr was lying across the doorway, and even Ephaniah was breathing peacefully, Septimus took out the Questing Stone. Jenna stirred and he quickly shoved it back into his pocket - but not before he saw that the yellow had deepened to a dull orange: "Orange to warn you that over you'll go." And now Septimus knew exactly what that meant.

Septimus woke the next morning feeling groggy from the musty fumes of the Foryx skin. It was still dark inside the tree house and the only way that Septimus could tell it was morning was by the presence of a small orange cat mewing impatiently to be let out. He lifted a corner of the Foryx skin door and, tail up, Ullr stalked out into the morning air. A moment later the cat landed with a soft thud in the snow below the tree and set about hunting for a more interesting breakfast than dried fish.

Unskilled in the art of hunting tree voles, the occupants of the tree house had to make other arrangements for breakfast. They set to heating some water and wondered if dried fish could be made more interesting by boiling it up with toffee. Jenna thought not, although Septimus liked the idea.

Beetle woke with a headache and a stiff neck and grumpily refused both fish and toffee, either separately or together.

Septimus put an end to the fish-or-toffee discussion by using the pan of boiling water for an infusion of strips of willow bark from his Physik tin. He made Beetle drink it. It was bitter and made Beetle gag, but half an hour later his headache and stiff neck were better and he was helping Jenna open three more of Sam's packages. They discovered some tiny sticky raisin cakes that Melissa had made for Jo-Jo, and a long strip of dried bacon. Suddenly breakfast seemed a lot more interesting.

Septimus decided to take Ephaniah's pulse; he wondered if it would be in the usual place. It was, even though his wrist was covered with soft rat fur. The pulse was weak but regular and Septimus was sure that Ephaniah was now in a deep sleep and not unconscious, but he could think of nothing in his Physik tin that would be of any help to the rat-man. It was, he thought, a question of time and, later on, something to stop the recurring nightmares that always afflicted those who had been InHabited.

About midmorning - according to Beetle's silent, tick-free timepiece - they had finished breakfast and decided that the only thing they could do was leave Ephaniah in the tree house to recover, and call for him on the way back. "Nik's really strong," said Jenna. "It will be so much easier with him to help get Ephaniah back to the Forest."

Septimus said nothing. He didn't think they'd be coming back at all, let alone coming back with Nicko, but Ephaniah was as safe in the tree house as anywhere - safer, in fact, than they were going to be.

Jenna kneeled beside the rat-man, covering him with their wolverine cloaks and making him comfortable. "Good-bye, Ephaniah," she said. "We've got to go, but we'll be back soon." Ephaniah's whiskers twitched and Jenna stroked his forehead. "You'll be fine," she said. Ephaniah half opened one eye. "He's waking up!" Jenna gasped.

Ephaniah seemed to be trying to focus on Jenna. He groaned and lifted his hand restlessly. Jenna took his hand and laid it gently back on his chest, but Ephaniah resisted. Jenna let go and watched his long, bony fingers scrabble inside the folds of his robes around his neck. "What is it?" she asked. "Does your neck hurt?"

In answer, Ephaniah drew out something from a hidden pocket and pressed it into Jenna's hand.

Then, with a long sigh, he closed his eyes and fell into a deep sleep.

Jenna stared at her hand. On it lay a slightly shiny circle of paper covered in a mass of finely detailed pencil lines. For a moment Jenna wondered what it could possibly be, but only for a moment. And then she knew - it was the missing piece of the map. It was the House of Foryx.