Mark hesitated as he saw the needles in Robb's thighs and the I.V. tubes attached to them. "What's going on?" he asked.

As Mark settled himself onto a rowing machine that was an exact twin of the one Robb was using, and one of the aides began adjusting it to fit his body, Ames explained the monitoring system and its purpose.

"We need to know exactly what happens to your body when you work out. The easiest way to do that is to analyze the chemical changes in your blood. And for that," he added, grinning in a parody of sadistic pleasure, "we have to puncture your veins and stick needles in your flesh."

Mark chuckled at Ames's exaggerated villainy, but still winced as the needles were slipped into him then taped securely in place. A moment later, as he began rowing, the first of the images flashed on the screen, and soon he found himself involved in the illusion that he was actually competing in a race with other rowers.

He leaned into the machine, increasing his pace, and a sheen of sweat broke out on his brow.

Then, as one of his two-dimensional competitors slipped by him on the left, he felt a surge of anger. Swearing silently, he pulled yet harder on the oars and a moment later overtook the image on the screen.

He rowed steadily for a while, keeping pace with the other oarsmen, but then they began to creep up on him, and he felt his anger begin to grow once more.

Almost imperceptibly, the image on the screen flickered. It happened so quickly that Mark was barely aware that it had occurred at all. The other boats were gaining on him now, and the muscles in his arms and legs were beginning to ache. Sweat dripped from his forehead, stinging his eyes, and he could feel it running down his back and under his arms as well.

The image on the screen kept flickering, but he was oblivious to it, his anger growing steadily as the other boats inexorably overtook him. He was furious now, almost trembling with the rage he felt toward the other rowers.

Then, slowly, he began to think of his mother.

He didn't know why she came into his mind, for he was totally unaware of her image as it was flashed subliminally on the screen, far too quickly and too briefly for his conscious mind to register.

But deep inside himself he was becoming convinced that it was her fault he was losing the race against the other rowers.

Her fault-for babying him all his life, for making excuses for him, for insisting that he was different from the other kids.

But he wasn't different.

He was only smaller, and weaker.

He rowed harder, grunting with the strain, trying to catch up with the other rowers. He would catch up-he knew it.

He was growing now, and getting stronger, and maybe it wouldn't happen today, but in the end he would win.

And he wouldn't let his mother stop him.

An hour later, after Mark and Robb had left the sports center and were on their way home, Marty Ames called Jerry Harris. "I think it's going to be all right," he said. "I have a feeling our latest problem may just solve itself after all."

Ames smiled to himself as he hung up. The experiments with Mark had taken a new turn. He was already feeling the tingle of anticipation that always came to him when he was on the verge of discovering something absolutely new.

If it worked-if the aggression that he was able to induce in his subjects could truly be focused on a specific object…

He put the thought out of his mind, refusing to savor it fully until he knew whether or not the experiment had succeeded.

Kelly Tanner knew they were out there, knew the creatures were hunting for her. She didn't know how she'd gotten there-wasn't even quite certain where she was.

Mark had taken her for a hike up in the hills, and at first it had been fun.Chivas had been with them, and they'd followed the stream up into the hills and found a little waterfall. A grove of pines was clustered around the pool beneath the falls, and she and Mark had sat down in the scented bed of needles beneath the trees whileChivas sniffed around the boulders at the edge of the river, scratching at a hole some animal had dug there. Suddenly Mark had picked up a rock and hurled it atChivas. The dog, yelping in pain, had whirled around, crouching low to the ground, stared at Mark for a moment then slunk off into the woods.

"Why did you do that?" Kelly had asked.

Mark hadn't answered her. Instead, he'd just gotten up and walked away, disappearing into the foliage afterChivas.

She hadn't liked that-she knew Mark wasn't supposed to leave her alone-but at first she wasn't worried. He'd come back in a few minutes, she thought, andChivas would be with him. Then they'd start back home.

But Mark hadn't come back. She'd waited and waited. And suddenly everything had changed.

The branches of the pines-so sheltering only a moment before-now seemed like arms reaching out to grab her.

The sun, too, had disappeared, and at first she thought it was nothing more than a cloud drifting by. But then the darkness had closed in on her and she felt the first pangs of fear.

She called out to Mark then, but there was no reply.

She scrambled to her feet. All she had to do was follow the stream, and pretty soon she would be out of the hills and back in the valley, and there would be the familiar houses and stores of the town.

Except that as she walked, the trail seemed to change, growing narrower and narrower, until she could barely make out where it was at all.

That was when the sounds had started.

They were faint cries at first, coming as if from a great distance away. Then she heard them again, nearer this time, and Kelly froze in the path to listen.

The sounds came ever closer, and began changing.

First they were moans-strange, strangled sounds, like someone crying. But then the moans shifted into a cacophony of shrieks that echoed in the hills around her, and Kelly shuddered.

She searched the cloying darkness around her, looking for the source of the terrifying sounds.

A twig cracked somewhere behind her, and she spun around, but could see nothing.

Another twig cracked, but this time the sound came from a different direction.

She started running then, but every step seemed to take forever. Her feet felt heavy; she could barely move them. She tried to cry out herself, tried to scream for Mark to come and help her, but her voice strangled in her throat and all that emerged was a faint rasp.

They were all around her now-whatever they were-and she thought she could hear them sniffing at the air, searching for her scent.

She knew what would happen when they found her. They would circle around her, closing her in, then come to get her, their yellow eyes glowing evilly in the darkness, their fangs dripping with saliva.

Suddenly she saw one of them.

It was big-bigger than anything she'd ever seen.

It had long arms, with curving claws extending from the fingers, reaching almost to the ground.

It was grunting, pushing its way through the brush, and she could smell a sour odor in the air as it breathed.

It was almost there, almost upon her, and she gathered what was left of her strength for a final scream.

That was when she woke up, her whole body jerking in a spasm of fear.

In the darkness the image of the monster still lurked, and in the distance she could still hear the cries of the others. She whimpered, gathering her blanket close around her, and then another, softer scream burst from her throat as her bedroom door opened.

"It's all right, darling," her mother told her, snapping on the ceiling light and filling the room with a brilliant glow that washed away the terrifying shadows. "You were just having a nightmare, that's all." Sharon came and sat on the edge of the bed. She put her arms around her daughter and held her close. "Do you want to tell me about it?"