Adric's head was throbbing. He lay on his right side, and the only sensation he felt was pain. He forced himself to open his eyes, and he tried to call out, but his voice refused to come.

In the gray dawn light, he saw vague shapes moving toward him. He heard sharp barks and yips and saw the dogs' eyes reflected in the waning moonlight.

Adric shifted, testing his left arm and leg. They were sore but functional; he had not fallen directly on them. With a groan he turned over, blinking against darkness that threatened to steal his consciousness, and swallowing to refuse the waves of nausea that roiled through his stomach. When he had managed to roll onto his left side, his eyes searched the huge rock face. Only a few feet away there seemed to be an indentation in the rock. Perhaps it was a cave.

Adric dragged himself toward the hollow. Panting, with sweat and blood dripping into his eyes, he pushed himself into the indentation with his left leg. He blinked back tears as he realized that there was no cave, merely a concavity in the rock, less than three feet deep.

He could hear the dogs' breathing and their excited yaps as they neared him. Blood dripped into his eyes, and he shook his head to clear his vision. Deep red drops fell onto the smooth rock; they disappeared instantly into the stone. Adric pressed his left hand against the cool surface. Beneath his fingers he felt several bumps. He traced them with his fingertip. They seemed to be the same circular shapes that comprised the characters in the dwellings. There were three rows of them. Without conscious thought, his fingers touched two shapes in the top row, then two more in the second row. Finally he pressed his fingertips against three more figures in the third row.

With a gasp, Adric felt complete and utter darkness envelop him.

The wild dogs stood before the hollow, sniffing the air that still held the scent of their prey. In confusion and frustration they whined, finally loping away from the empty indentation in the rock.

High above, Nyssa lay awake on her thin bedroll. Tegan was talking in her sleep. She seemed to be immersed in a dream which involved some sort of argument. Nyssa thought of waking her friend, but after a few minutes Tegan slipped back into quiet slumber.

Nyssa closed her eyes, but a plaintive canine whine drifted up from somewhere below. The sheer desperation and sadness inherent in the noise sent a shiver along her spine.

----------

As daylight seeped into the dwellings, the Doctor stepped to the doorway of the large chamber and looked out at the pale blue, cloudless sky. He ambled along the path to the home where Adric had spent the night, calling the boy's name as he entered the dwelling.

"Adric?" he repeated, looking about. The bedroll lay on the floor, but Adric's notepads and flask were gone. A single sheet of paper was anchored to the bedding with a stone.

The Doctor bent to pick up the sheet, reading the words quickly. A scowl deepened into his brow as he left the home, walking briskly toward the dwelling where Nyssa and Tegan were. His hand clutched the note.

He found the young women awake. Nyssa stood near the back wall, gently scraping at the stone. Tegan was rummaging through the satchel. When he entered, she looked up, saying. "I don't suppose you thought to bring any coffee or tea."

"No," he said tartly, "I didn't. The caffeine would diminish the hydrating effects of the beverage you've been drinking. Have you seen Adric?"

Nyssa looked up from her work. "No, not since yesterday afternoon."

Tegan took a long drink from her flask. "He isn't with you?"

The Doctor shook his head soberly. "He wrote that he's gone back to the TARDIS." His gaze fixed on Tegan; he was frowning.

Tegan stood and pointed at the note in his hand. "Is that from him?" She stepped forward quickly and snatched the page from him, reading rapidly. She glanced at Nyssa then crumpled the paper into her palm.

Nyssa had ceased her work. "What's the matter?" she asked. "What did he write?"

Tegan shook her head. "He wants to work by himself for a while."

"That's strange," the young Traken said. "He usually likes our company."

The Doctor was still frowning at Tegan. "Come on," he said brusquely. "We're going after him."

Tegan could already feel heat oozing into the dwelling; the early warmth, she knew, was a precursor to another intensely hot day. She took another sip from her flask, then commented, "If he wants to be alone, maybe we should let him be."

The Doctor shook his head. "No. I don't want us to be separated while we're here. We all need to remain together."

He had already turned toward the doorway. Nyssa and Tegan followed him outside. He was checking the metal hooks that held the ladder in place against the rock.

"You first, Nyssa," he instructed. She began climbing down. The Doctor kept his eyes focused on Nyssa; Tegan could tell that he was avoiding her.

When Nyssa had descended half-way, Tegan said, "I suppose you think this is somehow my fault."

The Doctor's gaze remained on Nyssa. "It was you who insisted that I speak with him. His departure is obviously connected to the conversation."

"Exactly what did you say to Adric yesterday?"

The Doctor looked at her, finally; his expression was still dark. "We had a very rational conversation."

"Rational? I see. And how was he feeling afterwards?"

"He was fine." The Doctor's tone was adamant.

"Really? Are you sure?" Tegan's voice now had a hard edge. "I think if he'd been fine he wouldn't have gone off to the TARDIS alone so that ... how did he put it? 'So that Nyssa and Tegan won't have to be bothered by me anymore.' Please don't tell me that you let him know that I'd noticed his behavior."

"Of course I did!" the Doctor snapped. "It was you who insisted that I initiate the discussion with him—"

"But in a sensitive way! You weren't supposed to make him feel embarrassed or self-conscious!"

"If you hadn't forced me into the conversation—if you'd permitted me to handle the situation as I saw fit, this would not have happened."

"Oh no, Doctor, don't blame this on me!" Tegan's voice had risen considerably.

"Doctor!" Nyssa called from the ground. "Tegan! What's going on?"

The Doctor gripped the hooks tightly. "Climb down."

"Look, Doctor, I—"

"Just climb down, Tegan." His tone remained firm, and he kept his gaze focused on the ladder.

With a shake of her head, Tegan began to descend. When she reached the bottom, Nyssa greeted her with concern.

"Is everything all right?" Nyssa asked. "It sounded like you and the Doctor were arguing."

Tegan shrugged.

"Was it about Adric? What did he write in the note?"

Nyssa reached for the wad of paper sticking out of Tegan's waistband, but the Australian took a step back. "It's not important. He just said he wanted to work alone for a while."

Nyssa clasped her hands together. "Oh dear. He wrote something about me, didn't he? Did I do something to upset him?"

Tegan shook her head. "No, Nyssa, you didn't. It certainly wasn't you."

The Doctor was nearing them rapidly. Tegan stepped to the side and waited until he had reached the ground. When he and Nyssa began walking, she followed several paces behind, taking a long drink from her flask. The cool liquid was somewhat soothing and seemed to help her feel a bit calmer.

The Doctor and Nyssa focused their conversation on Nyssa's analysis of the rocks. Tegan could not hear all of their discourse, but snippets reached her ears. Nyssa was saying that the composition was fairly standard with one exception. She mentioned something about organic matter, but when she began describing the chemical structure, Tegan's mind wandered.

The day grew increasingly hotter. As the sun rose, heat seemed to radiate from the dry, red earth. Tegan's hair was plastered to her forehead, and her shirt was drenched. She lifted her flask once again, but only a drop fell from the tip. She shook the container in some disbelief; it was empty.

The Doctor and Nyssa were well ahead of her. She remembered his admonition to conserve the liquid; she did not dare tell him that hers was gone. Besides, when they reached the TARDIS she would simply fill her flask with water, which would certainly be sufficient to see her back to the dwellings. She trudged ahead, wiping her hand across her face to keep the sweat from dripping into her eyes.

Perhaps half an hour later, the Doctor and Nyssa stopped walking. Tegan had kept her eyes focused on the ground to avoid the wicked glare of the sun. She bumped into the Doctor's back abruptly, then took a step back with a brief, "Sorry."

"You really should watch where you're going," he chided.

"Why are we stopping?" she asked.

The Doctor's eyes swept over the arid earth. Small tracks left by insects, birds, and reptiles peppered the rusty dirt. "There are no new footprints," he responded. "Adric didn't come back this way."

"Maybe he took a different route," Tegan suggested.

The Doctor shook his head. "There would be no reason for him to do that. Following our tracks would be the easiest way to get back to where we landed."

"So you don't think he came this way?" asked Nyssa with concern.

"No," said the Doctor, "I don't."

"We're nearly back to the TARDIS now," said Tegan. "Let's just check to see if he's there—"

The Doctor had already turned around. "He's not. Come on. We need to retrace our steps and see if he veered off of the path at any point. I should have been looking for that earlier."

"But surely we can just check in the TARDIS—" Tegan began to protest. The empty flask dangled from her hand.

"No," the Doctor stated. "We can't afford to waste the time. It would require at least an hour round-trip, and if Adric is out here somewhere wandering in the desert we need to find him as soon as possible."

Tegan's throat felt impossibly dry. She croaked out, "But you could just move the TARDIS closer—"

The Doctor turned toward her. "I told you yesterday that I cannot do that without risking damage to the ruins." His tone reminded her of a parent lecturing a small, intractable child. "Come on."

He walked quickly back over the dusty path in the dry earth. Tegan stood still for a moment, gazing in the direction of the TARDIS. Perhaps she should return to it anyway. She was tired of the Doctor's attitude toward her. She had only meant to help Adric; any discomfort he drew from the Doctor's words was certainly not her fault.

Nyssa touched her arm lightly. "He's not really angry with you, you know."

Tegan scoffed. "He could have fooled me."

Nyssa shook her head. "He's just worried about Adric. He feels that we are all his responsibility—he's concerned that he hasn't lived up to that."

The young women began walking again. Tegan was frightfully thirsty, and she considered asking Nyssa for a sip from her flask, but she dreaded having the Doctor know that she had failed to conserve the precious liquid as he had instructed.

She trudged ahead in silence, wiping her hand across her brow as she had done every few minutes for the past hour. Her forehead was dry. At least, she thought, she had stopped sweating. That would surely conserve some of her body's natural hydration. She moved ahead in the shimmering waves of heat.

----------

Adric's consciousness returned to him gradually. Utter oblivion was replaced with vague sensation, and this seemed somehow to expand outward through his limbs into genuine pain. He remembered, then, that he had fallen a great distance and that he was hurt. His right arm and leg throbbed now, and his head ached fiercely.

Hesitantly he opened his eyes. A vast expanse of pale purple stretched across his field of vision. He blinked; perhaps he was dreaming.

He moved his eyes to the side and saw a blur of yellow. He forced his vision to focus and realized that a small clump of flowers grew near his head. Rolling his eyes forward again he saw the lavender sky arching overhead. To his left lay towering mesas, but they seemed somehow different from those he had explored. The rock was a deeper shade of red, nearly crimson. Perhaps this was merely a trick of the light. He had not seen the landscape of Anahsti in the morning yet.

Nearer to him he saw more flowers struggling upward in the dry, rosy dirt. He rolled his eyes up to see what lay above his head. A sheer, rough rock face stretched upward toward the sky. There seemed to be a deep shadow, though, sheltering his head. He moved his left hand and felt stone beneath his body.

The pain in his limbs was intensifying. In a weak voice he managed to call out, "Doctor! Nyssa!"

The effort exhausted him, and he permitted his eyes to close. When he heard soft voices and felt gentle hands touch his shoulders, he allowed himself to slip fully into sleep. He was in his friends' caring and capable hands now.

----------

Tegan shuffled behind Nyssa through the hot, dry sand. They had veered off of their path and were now making a large semi-circle in the hope of finding some trace of Adric. The Doctor was making a similar detour in the opposite direction.

Tegan kept her eyes on the ground. The dull colors seemed to blend together, and after a time she was aware of nothing but her own listless forward movement. A flash of Nyssa's foot would snake across her line of sight occasionally so that she knew in which direction to move; she had to follow Nyssa. That much she remembered.

There was something she had meant to ask Nyssa. For some time she tried to recall what it was, but her mind seemed to break the thought apart into ever more desultory fragments that floated away from her consciousness. When Tegan heard voices, she forced herself to look up.

The Doctor and Nyssa stood several feet from her, talking. She blinked and tried to listen to their words, but all she heard was the shifting of the sand under her feet.

"Tegan, please try to keep up." The Doctor's importunate voice was suddenly clear.

She lifted her eyes; her companions were walking ahead of her.

"It's so hot, and I'm tired," she heard herself say rather plaintively.

Without glancing back, the Doctor snapped, "We're all tired, but we have to find Adric. Come on."

Tegan moved forward, keeping her head down against the harsh glare of the sun. The light made her forehead throb, and she could feel her heart pounding. Again she thought that she needed to speak with Nyssa, but she did not know about what. Her empty flask was still gripped tightly in her dry hand.

When the mesa with the dwellings in which they had worked loomed above them, the Doctor stopped. He looked about, shaking his head in frustration.

"There is no trace of him between here and the TARDIS," he said to Nyssa. "He must still be here. Adric!"

Nyssa called out the boy's name, too, but their voices echoed and died in the expanse of space between the mesas. The Doctor walked toward the ladder then tilted his head back to gaze up the face of the rock.

"Nyssa, there."

He pointed to a small tree that had managed to grow outward from a crevice about half-way up the face of the mesa, perhaps twenty feet from the ladder. The slim trunk had snapped, leaving the scraggly head of the tree dangling.

"What do you think it means?" Nyssa asked.

The Doctor's voice was sober as he replied, "I'm afraid it means that he fell."

"Fell?" Nyssa pressed a hand to her chest. "From up there? Oh no. It's so far—"

He nodded somberly. "Yes, it is." His eyes began to search the ground. After a minute, he walked several feet and touched the earth. When he lifted his hand, Nyssa saw a smear of red across his fingers.

"It's blood," he said, then he looked upward again.

Nyssa had paled, but she said, "If he were hurt very badly he would still be here, wouldn't he? He wouldn't be able to move."

The Doctor was pointing at the ground. "There's more blood here. The earth has been disturbed, too. It looks as if he was able to move in this direction." After a moment he had positioned himself near the indentation in the rock.

Nyssa turned to beckon Tegan, who stood several yards away. "Tegan!" Nyssa called. "It looks like Adric fell."

Tegan took a step forward then sank to her knees.

"Tegan!" Nyssa began to run toward her friend as Tegan's torso slipped down to the ground.

"Doctor!" Nyssa yelled over her shoulder.

The Doctor turned to stare at the fallen woman, then he sprinted forward. Nyssa had dropped down beside her friend, cradling Tegan's head in her lap. She placed her hand on Tegan's flushed cheek.

"She's terribly warm," Nyssa informed the Time Lord as he knelt next to her.

The Doctor rested his palm against Tegan's temple, then he brushed his fingers over her forehead. "She's stopped perspiring," he said. His other hand pressed against her neck. "Rapid pulse—flushed skin," he muttered.

"What's the matter with her?" asked Nyssa. "Is it the heat?"

He looked up. "She has all the symptoms of heatstroke. I should have seen the signs earlier."

"But the liquid you gave us should have kept her hydrated," Nyssa said. She took Tegan's flask, which lay at her side, and shook it. "It's empty."

The Doctor snatched the container from her hand. "Foolish girl! If she'd done as I told her and taken small sips— Why doesn't she ever pay attention to what I say?"

Nyssa's expression showed concern and sadness. "Please don't be angry with her, Doctor."

He was lifting Tegan into his arms, but he offered a glance at Nyssa. "I need to move her to the shade," he said, already beginning to walk quickly toward the shadow at the base of the mesa.

Nyssa followed him. He set Tegan on the ground and quickly began unbuttoning her blouse. "Go up to the dwelling and get the extra flash from my bag," he said curtly, then he removed Tegan's blouse and handed it to the young Traken. "And saturate this with water. Your shirt, too."

Nyssa took the garment from him.

"Hurry, Nyssa! We haven't any time to spare!"

Nyssa obliged and hastened toward the ladder. She climbed quickly and dashed into the dwelling. A minute later she descended the ladder, carrying the two wet shirts and the Doctor's flask. She held Tegan's empty flask, now full of cool water, as well, but this she dropped over the ledge to provide herself with a free hand for climbing. When she returned to her companions, the Doctor was fanning Tegan with his hat. He took the shirts and tucked one around her back and under her arms and the other around her hips. He paused to touch her hand. Nyssa watched as he gently pinched the skin; it remained standing.

"She's very dehydrated," he said, moving to lift Tegan's head with his hand and rest it in the crook of his arm. He held the flask to her lips, parting them with his fingers and squirting a small amount of the liquid into her mouth. He stroked her throat, murmuring, "Come on, Tegan. Drink."

"Will she be all right?" Nyssa asked anxiously.

The Doctor did not look at her as he replied, "She really needs intravenous fluids, but we don't have access to that here."

"I could go back to the TARDIS—" Nyssa offered.

"No, there isn't time. We must rehydrate her immediately." He allowed a few more drops to fall between her lips.

"Keeping her cool is important too, isn't it?"

The Doctor nodded.

"It's much cooler in the dwellings. Perhaps we should take her up there. She'd be near the water, too. We could put her in a cool bath."

The Doctor frowned then glanced up at the broken tree. "I don't want to risk carrying her up."

"Could we make some sort of sling for her?"

The Doctor passed the flask to Nyssa. "Yes, that's a good idea. I'll see what I can do." He stood then bent to lift Tegan again. "I'm going to move her to that hollow," he nodded toward the indentation in the rock. "It should be several degrees cooler in there." He carried Tegan a few yards then settled her into the smooth concavity, once again arranging the wet garments over her body.

Handing the flask to Nyssa, he said, "Continue to give this to her." He walked away quickly.

Nyssa sat next to Tegan, dribbling liquid into her mouth. "You must drink this," she enjoined. "Please, Tegan, you must."

After several minutes, Nyssa was satisfied that Tegan had swallowed a good quantity of the fluid. The Australian's cheeks were still flushed and hot, however, and Nyssa thought that bathing her face in water might help. She stood to retrieve the flask that she had dropped; she could see that it had bounced several yards beyond the bottom of the ladder. She stepped away. "I'll be right back," she said gently.

Tegan was vaguely aware of Nyssa's voice, although she could not understand the words. Her eyelids were much too heavy to open, but her fingers moved slightly, caressing the sleek stone against which she rested. Beneath her fingertips she felt a small change in the texture of the stone; she traced over it. A flash of the carvings that she had copied in the dwellings entered her mind. Her fingers inched over the characters etched into the base of the hollow. She was not consciously aware of finding a pattern, but her hand seemed drawn to press against two characters in the top row, two in the second row, and three in the bottom row.

Tegan's eyes opened half-way as she felt her shoulders jerk back. The sunlight was extinguished in a sudden curtain of absolute darkness. Tegan gasped.

Nyssa bent to pick up the flask then turned toward the mesa. She blinked; the indentation in the rock was empty. For a split second she thought she saw a grayish mist floating in the hollow, but as she continued to watch, it dissipated in an instant. The flask dropped from her hand.