Alana officially moves in, with her things, and she and Tom resume their 8 year 'marriage', she asks Kyle if he can write her a prescription for her allergy, Tom reminds her that Kyle is only a doctor in their alternate reality, she remarks she must have had a brain freeze.
Diana finds out Maia has a rare type of pneumonia that can be treated, but it could be symptom for something more serious. Shawn and Lily converse over why he cannot heal and Shawn asks her not to tell anyone, around the world several 4400s have rashes on their arms, back at NTAC Marco tells Tom that over 300 have fallen ill.
Dennis Ryland returns to NTAC and notifies that he is assuming temporary command of NTAC to figure out what is causing this epidemic among 4400s.
Kyle visits the house of the man in jail for the murder of Jordan Collier and changes the tire of a woman living at it when she discovers it's been vandalised. Alana attends the 4400 Center and is left confused as she believes it is the Collier Museum of Art (from her alternate reality with Tom), Tom arrives and Alana gets slightly distraught, Alana's sleeve gets raised when he attempts to calm her down and he discovers she has a rash, like the other 4400s who are sick.
Dennis tells his staff that all the 4400 are to be brought back into quarantine at Camp Dekker, and that England and France are passing legislation to quarantine those 4400 in their countries and it is expected other countries will follow suit.
Tom and Diana talk to Matthew Ross regarding the 4400s and possible cooperation between the two organisations regarding those 4400s that are ill, seeking medical care from NTAC.
Richard takes over the running of the 4400 Center while Shawn is ill. Shawn goes into quarantine, while Richard gives a speech to the press stating that If you are sick the responsible thing to do is to report to NTAC, but if you are well, showing no symptoms, we ask you to consider this: Walking into quarantine is an easy step, but walking out might be considerably more difficult.' Dennis announces that in ten hours they'll start rounding them up.
Kevin Burkhoff visits NTAC eating a bag of 4400 peanuts and talks to Max Hudson, Kevin gives Max his notes but receives nothing in return; Diana and Tom turn to Marco to 'hack' NTAC to get the medical information Kevin requires.
Lily observes Isabelle's carer taking her to a basement room, she gets Richard who breaks down the door, and they find several people running tests on Isabelle with Matthew Ross, who gives them a speech on Isabelle being the ''Rosetta Stone of the 4400'.
Marco brings Kevin Burkhoff NTACs notes on the illness affecting the 4400, Kevin leaves in a rush. Richard reveals some facts to Lily about Isabelle.
Most of the staff at the 4400 Center await outside with their hands linked together as several NTAC vehicles approach with armed NTAC officers and gun men, Dennis Ryland tells everyone to holster their gun, and as they walk closer to the entrance the linked staff make way to allow them to enter; Matthew Ross welcomes Dennis as he, Tom and Diana walk in, Matthew tells Dennis that there are no 4400s here and he does not know where they went.
Richard tells his fellow 4400s of the safe houses Jordan Collier left behind, and if they have to, they will defend them selves. Kyle visits his new friend who slaps him and reveals she knows that he lied to her.
Kevin Burkhoff reveals to Tom and Diana that the thing killing 4400s is not a disease but a side effect, and that there is a synthetic substance in a 4400s blood, named Promicin-inhibitor, that is gathering in their lymph nodes, Diana states 'It's what's making them sick Tom states that NTAC should have known about this, Kevin replies that they do know and that it is all in the files he gives Tom.
Bryan picks Lily up to take her and Isabelle to somewhere safe. Tom and Diana talk and discover that for every check-up a 4400 is injected with the Promicin-inhibitor, essentially NTAC made them ill.