Chet got his coat from the top drawer of his file cabinet and cleared his throat several times. Still Jack did not respond. Finally Chet resorted to speech.

“Hey, old sport,” Chet called out. “How long are you going to work on that stuff?”

“Until I’m done,” Jack said without looking up.

“I’m meeting Colleen for a quick bite,” Chet said. “We’re meeting at six. Are you interested? Maybe Terese could join us. Apparently they are planning to work most of the night.”

“I’m sticking here,” Jack said. “Enjoy yourselves. Say hello for me.”

Chet shrugged, pulled on his coat, and left.

Jack had been through the charts twice. So far the only genuine similarity among the four cases was the fact that their infectious disease symptoms had started after they had been admitted for other complaints. But as Laurie had pointed out, by definition, only Nodelman was a nosocomial case. In the other three situations the symptoms had come on within forty-eight hours of admission.

The only other possible similarity was the one that Jack had already considered: namely that all four patients were people who’d been hospitalized frequently and hence were economically undesirable in a capitated system. But other than that, Jack found nothing.

The ages ranged from twenty-eight to sixty-three. Two had been on the medical ward, one in OB-GYN, and one in orthopedics. There were no medications common to them all. Two were on “keep open” IVs. Socially they ranged from lower- to upper-middle class, and there was no indication that any of the four knew any of the others. There was one female and three males. Even their blood types differed.

Jack tossed his pen onto his desk and leaned back in his chair to stare at the ceiling. He didn’t know what he expected from the charts, but so far he hadn’t learned anything.

“Knock, knock,” a voice called.

Jack turned to see Laurie standing in the doorway.

“I see you made it back from your foray to the General,” she said.

“I don’t think I was in any danger until I got back here,” Jack said.

“I know what you mean,” Laurie said. “Rumor had it that Bingham was fit to be tied.”

“He wasn’t happy, but we managed to work it out,” Jack said.

“Are you worried about the threat from the people who beat you up?” Laurie asked.

“I suppose,” Jack said. “I haven’t thought too much about it. I’m sure I’ll feel differently when I get to my apartment.”

“You’re welcome to come over to mine,” Laurie said. “I have a sad couch in my living room that pulls out into a decent bed.”

“You’re kind to offer,” Jack said. “But I have to go home sometime. I’ll be careful.”

“Did you learn anything to explain the central supply connection?” Laurie asked.

“I wish,” Jack said. “Not only didn’t I learn anything, but I found out that a number of people, including the city epidemiologist and the hospital infection-control officer, have been in there beating the bushes for clues. I had the mistaken notion it was a novel idea.”

“Are you still thinking of the conspiracy slant?” Laurie asked.

“In some form or fashion,” Jack admitted. “Unfortunately, it seems to be a lonely stance.”

Laurie wished him good luck. He thanked her, and she left. A minute later she was back.

“I’m planning on getting a bite on the way home,” Laurie said. “Are you interested?”

“Thanks, but I’ve started on these charts, and I want to keep at it while the material is fresh in my mind.”

“I understand. Good night.”

“Good night, Laurie,” Jack said.

No sooner had Jack opened Nodelman’s chart for the third time than the phone rang. It was Terese.

“Colleen is about to leave to meet up with Chet,” Terese said. “Can I talk you into coming out for a quick dinner? We could all eat together.”

Jack was amazed. For five years he’d been avoiding social attachments of any kind. Now suddenly two intelligent, attractive women were both asking him to dine with them on the same night.

“I appreciate the offer,” Jack said. He then told Terese the same thing he’d told Laurie about the charts he was working on.

“I keep hoping you’ll give up on that crusade,” Terese said. “It hardly seems worth the risks, since you’ve already been beaten up and threatened with the loss of your job.”

“If I can prove someone is behind this affair it will certainly be worth the risks,” Jack said. “My fear is that there might be a real epidemic.”

“Chet seems to think you’re acting foolishly,” Terese persisted.

“He’s entitled to his opinion,” Jack said.

“Please be careful when you go home,” Terese intoned.

“I will,” Jack said. He was getting weary of everyone’s solicitude. The danger of going home that evening was something he’d considered as early as that morning.

“We’ll be working most of the night,” she added. “If you need to call, call me at work.”

“Okay,” Jack said. “Good luck.”

“Good luck to you,” Terese said. “And thanks for this ‘no waiting’ idea. Everyone loves it so far. I’m very grateful. ’Bye!”

Jack went back to Nodelman’s chart as soon as he put the phone down. He was attempting to get through the reams of nurses’ notes. But after five minutes of reading the same paragraph over and over, he acknowledged he wasn’t concentrating. His mind kept mulling over the irony of both Laurie and Terese asking him to dine with them. Thinking about the two women led to pondering again the similarities and differences in their personalities, and once he started thinking about personality, Beth Holderness popped into his mind. As soon as he thought about Beth, he began musing about the ease of ordering bacteria.

Jack closed Nodelman’s chart and drummed his fingers on his desk. He began to wonder. If someone had obtained a culture of a pathological bacteria from National Biologicals and then intentionally spread it to people, could National Biologicals tell it had been their bacteria?

The idea intrigued him. With the advances in DNA technology he thought it was scientifically possible for National Biologicals to tag their cultures, and for reasons of both liability and economic protection, he thought it was a reasonable thing to do. The question then became whether they did it or not.

Jack searched for the phone number. Once he found it, he put through a second call to the organization.

Early that afternoon on Jack’s first call he’d pressed “two” for sales. This time he pressed “three” for “support.” After being forced to listen to a rock music station for a few minutes, Jack heard a youthful-sounding male voice give his name, Igor Krasnyansky, and ask how he could be of assistance.

Jack introduced himself properly on this occasion and inquired if he could pose a theoretical question.

“Of course,” Igor said with a slight Slavic accent. “I will try to answer.”

“If I had a culture of bacteria,” Jack began, “is there any way that I could determine that it had originally come from your company even if it had gone through several passages in vivo?”

“That’s an easy one,” Igor said. “We phage-type all our cultures. So, sure, you could tell it came from National Biologicals.”

“What’s the identification process?” Jack asked.

“We have a fluorescein-labeled DNA probe,” Igor said. “It’s very simple.”

“If I wanted to make such an identification, would I have to send the sample to you?” Jack asked.

“Either that or I could send you some of the probe,” Igor said.

Jack was pleased. He gave his address and asked for the probe to be shipped via overnight express. He said he wanted it as soon as possible.

Hanging up the phone, Jack felt pleased with himself. He thought he’d come up with something that might lend considerable weight to his theory of intentional spread if any of the patients’ bacteria tested positive.

Jack looked down at the charts and considered giving up on them for the time being. After all, if the opposite turned out to be the case, and none of the bacteria was from National Biologicals, perhaps he would have to rethink the whole affair.