Rose was suddenly exhausted. She sank down to the ground, stretching out her legs and leaning back against the stone wall. She closed her eyes for a moment, trying to process what the Doctor had just told her.

"So we aren't dead, yeah?" she reiterated; she needed to be certain she had understood that very important point.

"Not technically," he replied, crouching down at her side.

She patted the cavern floor absently, and he settled next to her with a sigh.

She said, "What do you mean, 'not technically'? And why'd you say we'll die if we stay in here much longer?"

"Not in here, Rose, in the crypt," he replied wearily. "They've put us—our bodies anyway—in the crypt. But it's airtight when it's been sealed, and even with significantly decreased respiration neither of us can survive in there indefinitely. The room's fairly small, and there are no other openings; I checked for that while we were in there before. So whatever oxygen's been let in when they opened the crypt won't last you more than five or six hours. I'll automatically switch to respiratory bypass, of course, but even so, I doubt I'll hold out for more than ten, possibly eleven, hours."

"How do you know that? I mean, how do you know we aren't really dead and this is some sort of afterlife?"

"Afterlife? Well, I'm sure it wouldn't be like this." He gave her a small, inscrutable grin, then his expression grew somber again. "But to answer your question more empirically, I'm basing my theory on the evidence I found in the crypt. Did you wonder why I insisted to Greare that any other bodies he found be put elsewhere?"

She shrugged. But now that she thought about it, she recalled that he had seemed upset, even angry, just before he had spoken those words to the constable.

"Both bodies," he continued, "showed distinct signs of rigor mortis. Greare said they'd been found three to four days ago. In humans, rigor mortis sets in after about three hours and persists for approximately thirty-six, then the muscles become more pliant again. The presence of rigor shows that that young man and woman were dead for less than three days, which means were still alive when they were placed in the crypt. They suffocated in there."

Rose's head dropped into her hands. "Oh God. That's awful. How could that happen?"

"I don't believe it was intentional. I don't think anyone realized that they were still alive. My guess is that they were in some deep form of stasis, with only the faintest life signs, probably not even detectable with the technology available here."

"I've heard that sometimes, a long time ago, people were buried alive because they were in really deep comas and everyone thought they were dead. Is it sort of like that?"

He nodded. "That's one theory behind the tradition of the wake in some cultures. The body remained unburied and uncovered for a time in case the person wasn't really dead. There was always the vague hope that he or she would wake up."

"So how do we make ourselves wake up?"

"That is the question of the moment," he replied obliquely.

"If we don't," she began hesitantly, "if we can't find a way, will we stay like this forever?"

He shook his head. "I don't think so. There's no one else down here. It seems fairly clear that the death of the body causes the complete cessation of the life force. My guess is that as long as the brain is alive, even at the lowest level, the basic energy source remains, rather like an electrical generator transmitting power so long as it's running. But once that shuts down, the connection is broken and…" He shrugged.

"What then?"

"Depends on who you ask. Christians and Muslims believe in an afterlife, Jews don't. Reincarnation is a central tenet of Hinduism. The Q'razalians have absolute faith in the melding of each spirit with a massive energy source that they believe powers their sun."

Rose said with mild exasperation, "That's not what I mean."

"Oh. Well, it seems fairly obvious that if our bodies die we'll disappear from here."

She waited for further information but received none, so Rose asked another question. "Are we really here in this cave?"

"Yes. Nearly all of our psychic energy has been trapped here."

"You mean our minds?"

"If you like, yes."

"But if we aren't in our bodies then why can we still feel sensations?"

"I'm not sure that we really can. It's probable that we're only experiencing what we think we should. That's why neither one of us realized at first that we had no heartbeats."

"And we don't need them because we're not in our bodies, right?"

"Yep."

"But we're both solid; we feel real." Rose reached for the Doctor's hand. "Why's that?"

"Well, it's the way we perceive each other. When you sensed my energy, you automatically formed an image of me, so that's what you saw."

"Before I knew you were here, all I could see was shadows."

He nodded. "Yes, same for me. But as soon as I became aware of your presence, I saw you, or at least the image of you that I would normally perceive."

"So the fact that I can feel you," she squeezed his hand lightly, "isn't real? It's just what I expect?"

He nodded. "At the moment, we're both just bundles of energy."

"And our bodies seem dead because almost all of our energy is right here. But why is there any left? Why didn't all of it get sucked down here?"

"That's a very good question," he replied. "And I think it's clear that the same thing happened to all the other victims. Their life essences were somehow taken from them, but just the tiniest bit remained, just enough to keep them minimally alive."

"So they might've recovered if they hadn't been put in the crypt," Rose finished somberly.

"Possibly."

"Unless they were cremated before they woke up."

They exchanged alarmed glances, and Rose shot to her feet. "We have to get out of here. We have to find a way—"

The Doctor stood as well. "Agreed, but panicking isn't going to help. We need to figure out why we're here, why this happened, both to us and to the others, because I'm quite certain that the answer lies in that understanding."

"But the others couldn't find a way out before their bodies died," she began.

He tapped at his temple. "Superior Time Lord intelligence," he reminded her with a small, smug grin.

"Right. So that's one difference, then, between you an' them."

"Yes," he replied rather absently, but then he shook a finger at her excitedly. "Yes, it is. Good thinking, Rose!"

"Umm…thanks."

He began to pace the cavern, hands clasped behind his back. "Differences," he repeated. "What are the differences? Time Lord, obviously. And human, which is of course a similarity, so that's not much help, is it? But we're here together, which is a difference, because based upon times of death, I think we're the only two who've been here at the same time. The others would've died one by one, before anyone else was taken. So what's that mean?"

"One by one," Rose reiterated. "It's like none of them worked out, sort of like trying out different workers in a job, or going to a different hairdresser each time 'til you find the one who does what you want."

"And why would you do that?"

"Colour's not quite right, cut's too short or too long," she ticked off reasons on the fingers of one hand. "Maybe you don't like their personality—"

He stopped abruptly and grasped her arms. "Yes, personality! You want them to understand you, to figure out just what you want even if you don't really know yourself."

She arched an eyebrow at him. "Have a lot of experience with hairdressers, do you?"

He snorted. "Me? Oh, this is all my own style. But I've travelled with enough women to have a basic understanding of the relationship between a girl and her stylist."

"Yeah. Anyway, back to why we're here and how we get out," she prompted.

"Right. Perhaps it all comes down to understanding. You asked what the point was in keeping all of the victims alive. What could the reason be?" He waited expectantly for her reply.

"It was trying 'thm out, trying to find the right one," she concluded. "Or maybe they all died before they could figure out why they'd been taken, so whatever did this had to keep taking new ones."

He tapped her nose affectionately . "Exactly! Question is, though, for what?"

"I dunno, but seems to me the more important question is by who. Who did this to us?"

"I didn't pick up any signs of humanoid life aside from us when I scanned the areas where the victims were found, so we may be talking about another sort of entity."

"Maybe something like what we are now? Just a big ball of energy?"

He patted at his pocket for a moment before sighing. "No sonic screwdriver."

"You couldn't use it anyway. No real body, remember?"

He looked at her intensely for an instant. "But lots and lots of energy, which is made even stronger because it's been freed from physical constraints. All those little bits that normally fuel the cells are concentrated right here. So my psychic energy should be stronger, too, because it's not tied to anything corporeal. And if I stop using the bulk of it to see you, I may be able to sense any other power sources in the area."

Abruptly he closed his eyes and lowered his head. He remained very still for some time then looked up at her. "I can almost feel it; it's just at the edge of my awareness.

But I'm having a hard time pulling completely away from you."

Rose frowned. "Why's that?"

"Your need to perceive me in some bodily form is drawing just a little bit of energy away from me. You have to stop doing that."

"How?"

"Just close your eyes and don't see me."

"I'll try." Her tone was less than convincing. It was one thing to believe that she and the Time Lord were separated from their bodies; it was quite another to give up the very image that gave her hope that things would return to normal. If she could no longer see the Doctor, maybe he would cease to exist.

"I'll still be here," he reassured her, apparently comprehending her anxiety. "But not for long if we don't figure this out."

Rose nodded and closed her eyes. She could still visualize his face and sense him beside her, but gradually the image began to blur. She envisioned the softening of the lines of his body, and as she did they grew indistinct and began to fade. She felt a wave of panic but quelled it as she recalled his final words. She allowed him to dissipate, to drift off in all directions.

His essence brushed against the walls, and she found herself drawn to follow him. She discovered that her body had vanished, too, and she floated across the cavern, spreading impossibly yet inexorably toward the wall just as he had.

The moment she touched the stone, she felt it. Rose was overwhelmed with the sensations of deep pain and pervading loss. Wrenching grief flooded her as she spread out over the surface. And the anguish was not singular; it emanated from all around, as though she were surrounded by the souls of a thousand, ten thousand, a million others, all crying out in anguish.

She remembered the plateau; the image of the jagged scar cut from the rock pulsed through her. She knew that she currently possessed no spoken language capabilities, yet still she whispered, "I understand."

Then she was coalescing, her energy drawn together once more, and the pain was fading, sensation scattering away. She wanted to fade away, too; the fleeting memory of the agony clawed at her, leaving her aching with loss. She could just float away, spread out so far that the pain would disperse into tiny bits, little harmless fragments of feeling…

"Rose. Look at me."

The Doctor's voice brought her back to the cavern in an instant. She opened her eyes. He was kneeling over her; she lay upon the floor. She reached up to touch his cheek, sighing in relief when her fingers felt the firmness of his skin.

"You're back," she said softly.

"So are you. I wasn't sure that you were going to return. You were gone for a long time."

"Was I?" she asked, sitting up and looking about. "We're still in the cavern, but you feel real."

"That's because I told you to look at me. You have to be able to see me in bodily form to do that." He smiled sadly.

"Doctor," she said, "I know why we're here."

He nodded. "I do, too."

She saw ineffable sadness in his eyes, and she knew that it was more than simply her perception. The emotion radiated from him as strongly as it did from her.

"We have to get back to the village; we have to tell Greare so he can stop it," she said.

"Yes," he agreed simply.

Rose got to her feet. "So they'll let us go now that we know," she said hopefully. "They'll send us back, won't they?"

"I don't know." The Doctor looked about then shook his head. "Perhaps they'd have done it by now if they could."

"What?"

"Now that we understand, now that we can stop the pain and damage, we should've been sent back to our bodies. There's only one reason I can think of that we weren't."

Rose waited. "Yeah?" she prompted.

"Maybe they don't know how. Maybe they're able to bring living energy in here but don't understand how to send it back."

"No… that can't be right. They showed us, brought us here to understand, and now they have to let us go back."

"I'm not sure that they can."

"Then we have to find a way." She was already walking toward the tunnel, peering through the shadows in the hopes of perceiving an exit. "I came in through here, I think."

She found that the tunnel ended in solid rock. There were no additional openings, no side passageways. When she turned back to the entrance to the cavern, she saw the Doctor standing there.

"No exit?" he asked.

She shook her head. "But this is where I came in. There's gotta be a way to get out."

He joined her in the tunnel, looking about carefully in the dimness. "I was in the cavern when awareness returned to me. I suppose I could've entered here, though. I felt as though I were moving before I was able to perceive images."

Rose trailed her fingers over the wall. "How can we see?" she asked, momentarily distracted from the issue at hand.

"Oh, we can't, really. But we can sense matter all around us, so we automatically create images of it. Perhaps, too, the entity that brought us here is helping us to 'see' through some sort of psychic connection."

"But what we're seeing, that's really what's here, right?"

"More or less."

"Then we should be able to find where we got in. We couldn't go through solid rock, because energy is still a form of matter, right? So there must be some opening, some little crack—"

"The breeze," the Doctor interjected. Before she could ask for clarification, he added, "When we first arrived on the planet, you said you felt cooler air near the base of the wall. That must've come from in here."

He walked the length of the tunnel scrutinizing the walls and ceiling. Finally he pointed above his head. "That's it. There's a tiny fissure just there."

Rose peered through the gloom, but she could see nothing. "If you say so."

"I do. And I think the wall lies just beyond it."

"So we came in there. Can we get out, too?"

The Time Lord stretched his arms upward, reaching toward the ceiling. He closed his eyes. "No," he murmured, "I can't…"

"Doctor?"

He sighed in frustration. "The connection's too weak. We're going to have to be closer to our bodies. If the wall runs along here," he gestured again, "then the village should be this way." He pointed to his left.

"All right. Let's go." She was already striding out of the tunnel and back into the cavern.

Rose moved carefully along the wall, hands pressing against the stone. She understood that she might not be able to see any openings or passageways, but she thought she would sense the change in structure. After a few moments she realized that the Doctor was examining the opposite wall, searching just as she was.

She could feel the solidity of the stone, and after a time she perceived a gap. She bent to squint at it, forgetting for an instant that the thought of the tiny action did not make it real. Still, she was certain that a small cleft lay before her.

"Over here!" she called, and suddenly the Doctor was beside her. "Right here." She ran her hand over the aperture.

The Time Lord thrust his arm out then grinned at her. "That's my Rose, always finding the loophole," he said. "And just in time. Come on!"

He took a step and vanished. Rose did not hesitate to follow him. She felt the bulk of the stone pressing in against her shoulders, but she was able to move forward without difficulty. She could see nothing, however.

"How big is this passage?" she asked.

"Oh, probably only a few centimeters wide," the Doctor replied airily.

"A few centimeters? But we're walking through it without any trouble."

"Remember, Rose, we're not really walking. Our energy is slipping through, and we don't need much space for that. Really a millimeter or two would've been more than enough."

Rose was sure she would never fully comprehend how she could be incorporeal. Indeed, a bit of light emanated from above, and she could see her hands as she lifted them toward her face. She watched in momentary fascination, utterly intrigued yet equally appalled by the knowledge that her real body lay on a cold stone slab that seemed impossibly far away…

She gasped suddenly as the appendages before her seemed to waver then fade. She focused her concentration on the image that she expected to appear, but her hands remained strangely translucent.

"Come on, Rose," the Doctor urged, aware that she has stopped moving. "There's no time for playing junior geologist."

"Doctor," she replied, and her voice sounded faint, "there's something happening… to me."