Starting on a personal note, the narrator conveys Jack's musings about Terese's unpredictability since she "agitated" him because she seemed attractive one moment and off-putting the next. Jack's wonderings switch to the puzzle of whom he offended so much as to have vandals and threats sent after him. With these thoughts inspiring his vague determination to "be careful," he pursues his decision for revisiting Manhattan General.
Two important pieces of information are developed in this chapter. One is that the hospital is doing everything possible to control the spread of contagions even going so far as the self-impose semi-quarantine enforced by city police on guard out-of-doors. This is an important idea to develop as we approach the upcoming moment when Jack uncovers who or what is behind the outbreaks of contagions. Is his theory correct that it is someone with limited knowledge of how contagion spreads, thus starting with a contagion that didn't spread human-to-human, who will next spread a human-to-human contagion, such as influenza?
The second is Jack's surprise finding at the ease with which pathogenic microbes can be ordered over the phone. Beth tells him that this can and is routinely done. Not believing the plausibility of acquiring life threatening pathogens with such simplicity and ease, he simulates a order himself by calling the number Beth gave him.
The route of Jack's actions in the chapter is that he enters Manhattan General and, seeing that everyone has been ordered to wear a protective medical face mask, he dons one too, then finds a white coat in his size in the Doctor's Room where laboratory coats are hung. He goes first to Central Medical Supply to talk again with the manager, Gladys, there who had helped him earlier (debatable move since she had also grown hysterical and complained about his supposed assertion that the infections were for a known fact generated by the hospital ...). What he learns from her is that the hospital staff is pursuing the same lines of inquiry he began with, including a check on the air circulation system.
Next he goes up to the laboratory and finds it filled with hospital staff. The reason is that every staff member is giving a throat culture to test for meningococcus. After safely getting through the crowd without being recognized, where even Martin is taking throat cultures, he finally finds Beth who tells him (1) that him he is really disliked by the administration and (2) that pathogenic infectious disease microbes can be ordered over the phone and can even be over-nighted for rapid delivery. On his way out, after placing his phone call and simulated microbe order, he is caught in the act of leaving the lab by Martin and Richard who are entering with trays full of throat culture swabs in their arms. Jack is trying to exit and they help him to do so after Martin first calls Kelley and complains very earnestly, the end result being that Jack is to be invited out by security guards, if they can catch him.
Jack dialed the number [to the pathogenic culture company]. The phone was answered and ... Jack pressed two for sales ... [a] friendly voice ... asked if she could be of assistance.
"Yes," Jack said. "This is Dr. Billy Rubin and I'd like to place an order."
"Do you have an account with National Biologicals??" the woman asked.
"Not yet," Jack said. "In fact, for this order I'd just like to use my American Express card."
"I'm sorry, but we only accept Visa and Mastercard," the woman said.
"No problem," Jack said. "Visa will be fine."
"Okay," the woman said cheerfully. "Could I have your first order?"
"How about meningococcus?"
"... We have hundreds of meningococcus subspecies."