Kayla checked her watch as she set down the last of the patient records. 4:45 and she was now off-duty.

She glanced around the new Trauma Center, which had opened only a few days earlier. "Tom Horton's pride and joy" was what people were calling it, and Kayla was thrilled that she could be a part of it.

After so many months as an administrator at the Immunology Lab and then, dealing with her suspension and the kidnapping, Kayla was enjoying her return to some real nursing work. Unfortunately, that included some of the drudgery that came with it; she had spent the last hour correcting the entries made by one of the trainee nurses. This nurse was either incapable of understanding University Hospital shorthand or just did not care. Either way, that kind of carelessness could cost patient's lives.

Finishing the records, she passed the files over to the nurse holding down the fort at the nurse's station. She yawned. It had been a long day and she was tired. Maybe she and Steve could just order some Chinese and spend the night in front of the TV.

"Oh, Kayla, Dr. Curtis left this for you." Another nurse had walked over to the station and was carrying some envelopes. "They're for the Immunology Lab. I guess they got misdirected."

Kayla had not been planning on going to the lab that day. Dr. Bishop and Brian, the new researcher, were attending a conference. Only Carly might be around and she was not really doing lab work at the moment.

"I can just put this in the inter-hospital mail," the nurse said.

"No," Kayla said, holding out her hand. "I'll take them down."

It would only be a few minutes, she told herself. Then I can go home.

She was soon at the lab, which was locked. Guess Carly must have left early, Kayla thought. Unlocking the door, Kayla walked over to the trays for incoming mail and began to sort the mail. She had only dropped the first envelope into Dr. Bishop's box when she heard the screams.

Kayla dropped the stack of mail and spun around. The screams continued. They were coming from the back of the lab, where it sounded like someone was in massive pain.

Without hesitating, Kayla rushed toward the sound. Carly! she realized. It had to be Carly. Nobody else could be in the lab. She raced down the hall that led to Carly's office and burst through the open doorway.

Carly was sitting at her desk, apparently so focused on the source of the screams - a television - that she did not even notice Kayla had entered the room. Kayla let out a relieved breath. She started to turn back, but then she caught sight of the image on the screen.

It was a dark-skinned woman, who was writhing on the ground in obvious pain. She was screaming as her body convulsed. Kayla had only heard screams like that from some of the most severely injured accident and fire victims. It was the sound of someone in such great pain that death would be merciful.

And then the screams stopped.

Kayla stared at the screen, at first certain that the woman was dead. But then she heard a heavily accented voice say, "Subject is now entering paralytic phase." At least that was what she thought she heard. The accent sounded Eastern European.

In front of her, Carly lifted a hand to her mouth. On screen, the camera moved closer to the woman. Now, Kayla could see that the woman was still alive. Her mouth moved only slightly, but, plainly, she was gasping for air. Both of her eyelids and the right side of her face were drooping, much like Kayla had seen happen with stroke victims.

She stepped forward to look more closely. The woman was still moving, but her body seemed to grow progressively still. Her arms stopped jerking around.

Nothing happened for several minutes. The woman's chest continued to rise and fall, so she was still breathing. But other than that, there was no apparent sign of life.

"14 minutes, 36 seconds," said the accented voice. "No lethality. Administer the antidote."

A white-coated and masked man came into view with a vial in his hand. He crouched next to the woman, forced open her mouth, and poured some liquid.

The voice said, "Initiate timing sequence now."

As Kayla watched, the woman appeared to stop gasping and began to stir. Her first sounds were a pained groan, but at least she was alive. Riveted to the screen, Kayla saw the woman slowly work her jaw, which had gone slack, and blink the drooping eyelids. Then she sat up, still weak and shaken, but in far better condition than before.

"What the hell-" Kayla said, before cutting herself off sharply as she remembered that she was not supposed to know about Carly's work.

Too late. Carly spun around. "Kayla!" Carly looked at her, then at the screen, then back at her. "How much did you see?" she demanded to know.

"Enough," Kayla admitted. "I . . . I heard screams and. . . well, I thought you were in trouble."

Carly sighed and ran her hands over her face. "You weren't supposed to see this."

"Too late," Kayla said with a shrug. She gave Carly a sympathetic glance. "I guess this has something to do with your top-secret project. I can see why it's been so hard for you."

"You have no idea." Carly looked down at the floor. "I can't even tell Bo about it, and day after day. . . ."

Kayla understood. "It wears you down. Can I help?"

"I'm not supposed to talk about it with anyone," Carly said. "This has some high-level security clearance."

In other words, it was ISA. Carly confirmed Kayla's suspicions. "You can tell me," Kayla urged. "I'm a member of the lab team and I'm not going to tell anyone."

Carly seemed to think for a moment, but then said, "I need you to promise. You won't tell a soul."

"Of course," Kayla assured. "What's going on?"

Pointing at the screen, Carly began to explain. "This video. . . . It came from a - well, that part I'd better not say. It was provided to us. We're researching a toxin, one that could be extremely lethal, particularly if it gets into the wrong hands."

"Okay. . . ." Kayla tried to fight the dread rising within her by forcing herself to keep calm and think rationally. "It could be lethal, but the video said it was not lethal."

"Not yet, apparently," Carly said. "But that could change any day."

Kayla took a deep breath. "Why do they have you working on this? Don't they have their own scientists?" She knew she did not have to say who "they" were. Carly would understand.

Carly stood up and walked slowly over to the VCR. She obviously was debating whether to respond. Finally, she said, "They think Salem's a target. I'm involved so if something happens, I'll know and can help with a response."

"What kind of response?" Kayla was beginning to feel sick. Salem? Someone's threatening to use this toxin on Salem? She thought about all of her family members and friends in the city. Any one of them could wind up like the woman on the TV screen.

Carly pointed to a wall of boxes. "Antidotes to possible toxins. We don't know what we're up against - though the video may help with that. We're guessing what's most likely to work, so we're stockpiling different antidotes. God . . . I shouldn't be telling you this."

Kayla walked over to her. "It's okay. I think you needed to talk. And you can trust me."

Carly started to reply, but her words were cut off by another round of screams. She and Kayla both turned to the screen where the woman was again convulsing on the floor.

"What the-" Carly said, her eyes going wide.

As they watched, they could see the symptoms returning. The woman's eyes seemed to close and her she began gasping for air once more. Several white-coated workers were around her and seemed confused.

Carly grabbed the remote and hit the "rewind" button. "I didn't see them give her more gas." She stopped the tape just after the man administered the antidote and they watched it again. Nobody seemed to do anything to the woman other than check her vital signs. But for whatever reason, she started convulsing and screaming again.

"Their antidote doesn't work," Kayla said, feeling the bile rise in her throat. What kind of sick monster tests poison on people without an antidote? What kind of sick monster tests any poison on people?

"No. That's not right. . . unless this is a different antidote." Carly shook her head. "This didn't happen to the other people."

The other people? Kayla had to close her eyes and swallow to stop from being sick. "There are others?"

"This is the third tape," Carly explained. "The others were fine."

They both continued to watch, transfixed. After a few more minutes, the woman began to grow still, the tremors slowing and her screams halting. There was some background noise, as if people were conferring, but the words were too faint to make out.

Then they heard the Eastern European voice. "Subject experienced relapse. Reason unknown. Relapse intriguing effect after long exposure that may warrant further study, but of minor concern for present project."

"Why isn't it a concern?" Kayla wondered aloud. As she spoke, the white-coated man administered more of the antidote to the motionless woman.

Carly answered Kayla's question. "You don't need to worry about the victims relapsing when they're dead." She sat back in her chair and they both watched as the woman was helped to her feet and taken out of the frame. A moment later, the image on the TV turned into snow.

"They don't need to worry about relapsing, but we will." Carly turned her head toward the stacked boxes. "How much antidote will we need per person? There's no way of knowing."

"At least, you know about it so you can plan." Kayla shuddered at the thought of the doctor giving people the antidote and thinking they are okay, only to have them collapse again.

With a sick realization, Kayla pictured a flood of patients being brought into the ER, unmoving except for the slight rise and fall of their chests. That's what could happen. That what someone wants to happen.

Carly had stood up and was flipping through a stack of papers. She was mumbling to herself, mostly unintelligible words, but Kayla heard "why" and "there's got to be a reason."

"A reason for what?" Kayla asked.

"Why that toxin keeps working after the antidote is given." Carly frowned.

Kayla did too. She thought about what she had seen, but she knew little about how poison worked. With a sigh, she said, "I don't know. It's like the poison is fighting back or hiding until the antidote passes by." Kayla kicked herself. "Sorry, that sounded pretty stupid."

"No," Carly said quickly. "That's it."

"What's it?" Kayla was baffled. She had just been making a bad joke.

Carly pulled out a notepad and began scribbling on it. "Some drugs get absorbed quickly into cells but can be released later. So, in effect, the toxin is hiding. Maybe once the body takes in the toxin at the places it attacks, the rest is stored and becomes inactive. When the antidote clears the active toxin, that cues the release of whatever is stored."

"Would it come back that quickly?" Kayla was skeptical of the idea.

"Maybe." Carly shrugged. "We don't even know what 'it' is." She groaned loudly. "Sometimes I wish I'd never signed onto this project." Shaking her head, Carly walked over to the VCR and ejected the videotape. "I guess I'd better call Washington."

Kayla took that as her cue to leave. "Okay. . . . But if you need to talk, I'm here to listen."

"Thanks," Carly said. "I do appreciate. And please don't tell anyone. This really has to stay a secret."

Kayla understood why. If word got out that the ISA suspected an attack on Salem with whatever poison was on that video, the entire city would panic. She nodded, turned to the door, and said, "I won't tell a soul."