Julia comes to in the shower to find Alan covering her with a towel. When he asks her what happened, at first Jules can't recall; then she does -- Peter virus-smooched her -- but lies to Alan that she felt faint.
Alan's hallway brooding is interrupted by mysterious clanking, and Alan follows it to a lab. Peter's virus super-speed lets him sneak up behind Alan; grunt, "Help...me"; and swoon.
Sarah is still pretending to ignore the twitching in her hand as Doreen impatiently explains to the restlessly quarantined natives that no, she can't "just" give them antivirals that aren't calibrated for Black Death 2K14. On the other side of the glass, Hatake basically ignores the latest report from Balleseros and Aerov on the escapees (hiding) and the outbreak (spreading) in favor of asking where Julia is, then saying he doesn't need to speak to her. Aerov doesn't understand Hatake's apparent crush on Jules any better than we do.
Just then, Alan wheels Peter into containment. Hatake isn't happy (is he ever?), and when Alan says Peter "turned himself in," Hatake and Aerov exchange a Look. Hatake isn't satisfied that Peter can be restrained, so Aerov gives everyone a tour of Level R, an older floor of the facility with concrete walls and steel doors. Balleseros wonders what kind of research required a nuclear reactor. Aerov reluctantly answers, "Controlled fusion," but claims the site is not dangerous, so Alan proposes during the entire level into an isolation floor for "vectors" (the name for the infected).
In the bathroom, Julia flips out and starts to see all kinds of symptoms in the mirror -- lesions, prominent veins on her arms -- and choke on that signature black vomit. It's just paranoia, though, and she orders herself to get it together: "You don't. Get. Sick."
Alan's explaining what he needs to turn Level R into a full-service plagueteria when he, Hatake, and the gang come upon one of the escapees, Dr. Sulemani. She begs for help, and when she gets too close to the group, Aerov shoots her in the stomach. Alan has to do emergency surgery on the hallway floor, assisted by Nurse Hatake. Afterwards, Alan explodes: no more lethal force! Hatake reminds Alan that, on the base, he is the law; Alan reminds Hatake that he can pull his team if Hatake doesn't play it his way.
Julia's at Peter's side, asking what he did to her. He mutters inaudibly. She gingerly leans down to listen, but is startled by Alan's disapproving knock before she can get any info. Alan briefs the others on the isolation floor, and tasks Julia and Sarah with creating a rapid-response test. Doreen wants to prove that the monkey version of the virus is ground zero so they can formulate a vaccine. Balleseros volunteers to go with her, and Doreen snorts that it's not necessary (possibly because he's acting very obviously untrustworthy), but Alan insists, then stares at Julia staring at Peter.
Alan and Aerov argue over their differing ideas of "security" in a hallway while, in a lab, Julia and Sarah argue over how best to build the test. Julia notices Sarah's hand shaking. Sarah says it's just sleep deprivation.
Doreen explains to Balleseros, and the viewer, how to stop a virus, then trails off when she sees the examination table is empty. "Where the hell is my monkey?" If we had a nickel... She's furious that the entire room's drenched in formaldehyde, and Hatake determined not to let her examine the monkey; she's fixing to chew Hatake out when Balleseros stops her, offering to get her another sample.
Julia remembers her crappy marriage to Alan as Peter has fever dreams and, outside, Doreen confronts Balleseros about how he knew where to find the frozen monkeys -- and what he's really doing there. He non-answers that some Army folk think Hatake released the virus on purpose. Why would he do that, Doreen demands. Help me find out, Balleseros proposes. Don't do it, Doreen!
Alan checks on Sulemani. Aerov reports another escapee has turned up on Level R.
Sarah's very proud of herself for cracking the test using a jellyfish enzyme, but when Julia asks for a demonstration using Sarah as a control, Sarah balks -- and suggests Julia swab herself to test the test. After a long pause, Julia assents. Sarah snots that that's a waste of time and goes to tell Alan, but Julia nads up and swabs herself anyway. It comes up negative.
The escapee, Bryce, is whacking on a fellow scientist's door with a fire axe and raving about the cure that's inside his quarters when Alan and Aerov come upon him. Then he swings the axe at them. Aerov tases him. The scientist creeps out of his room and unconvincingly denies that any cure exists.
Doreen tests the monkey blood -- and as Balleseros looks on, it grows roots and tries to escape its decontamination box. Only a shot of gas keeps the roots from breaking free. She wants to ask Alan about it, but Balleseros sketchily insists they keep it to themselves, lest Hatake shut them down.
When Alan threatens to rat Hatake out to the press, Hatake finally confesses that he's been testing a universal antiviral vaccine. Two problems there: he's hoarding illegal strains of deadly diseases like smallpox, to test the cure on; and the mortality rate of the vaccine is 75 percent. Alan is speechless.
Alan, Sarah, and Jules test everyone on the base. Forty-three people -- nearly a third of the personnel -- test positive. As Balleseros and Aerov exchange significant glances, Alan and Julia have a bonding moment, and then Sulemani attacks Aerov and escapes again, leaving Bryce dead in her wake.
Julia confronts a sweaty Sarah: is she infected? Sarah gets mad at the implication that she's unethical and tries to shame Julia into backing down, but Julia won't, so Sarah brats that she'll take the test. It comes up clear...but it looks like Sarah palmed the swab for a fresh one. Just then Aerov tells Julia that Alan needs to come deal with the Sulemani situation, but Dr. Marin overhears and does the Helix equivalent of screaming "FIRE" in a crowded theater, and chaos ensues.
The quarantined all rush for the exits. Alan can't get to Julia. Sulemani appears and attacks a guard, Aerov drops his gun in the scrum, and Julia freezes completely. Sulemani locks Julia in her gaze, then rushes her, but Alan shoots Sulemani (from behind Julia -- nice marksmanship). He's herding Julia into the elevator to go upstairs, but she shows him the black goo she's just coughed up. She's infected after all.
Hatake isn't happy (see?) about sealing off Level R, especially with Julia still down there. Alan and Aerov note that there's a week's worth of supplies on Level R, and Alan plans to call for Army backup when the satellite goes live. Balleseros, who apparently bought his fatigues at an Army-Navy store, looks shifty some more.
Sarah stares at herself in the mirror, near tears. Her hand trembles. She changes for bed, and reveals a gnarly scar running down her neck to her back.
Alan's depressed about killing Sulemani and losing control of the situation. Doreen bucks him up, but lies that examining the monkey told her nothing.
Julia wanders into the containment dorm, smearing black goo on her lab coat and acting stoned. As she's changing, she finds her quick test in her pocket. It's still clear. She rushes over to the rack of positive tests; they've all turned clear. "It doesn't work!" she grits, and dashes off to an emergency phone to tell Alan, but outside, Balleseros is bomb-rigging the satellite dish. It explodes; the call is cut off. Julia bellows and pounds on the door: "The test doesn't wooooork!" And help isn't coming.