The National Primate Research Center, Bethesda MD. A doctor releases the "latest" gas compound into a monkey's cage as military guys look on sternly (hey, someone's got to do the glaring without Aerov around). This 'X Gas' "kills everything it touches," the doctor says proudly as the screeching monkey is surrounded by smoke and starts to blister. Once the poor creature is dead, the doctor asks how many vials they need. "All of them," the general says in a tone of wonderment.
Peter cradles a baby. Anne calls Peter a natural with infants and a "born leader" who can rebuild Killigan's Island -- but they'll have to tie up some loose ends, "skeptics" who might interfere with their plans. Anne burbles that she'll stand behind his decisions regardless, letting him convince himself that the CDCers can't leave the island, lest they expose Peter 'n' Anne's Organic Baby Farm Basement.
Jules explains that they'll implant Sarah's baby into Amy with an artificial placenta and umbilical cord, and they'll have to amp her hormone levels to make sure the implant "takes." Jules says most of this absently while watching the away team filing in at the Abbey wall (Alan's telling Kyle he has to stay in restraints even though the red sap is "holding off the mycosis" for the moment, and Soren that they'll find his mom, but he has to help them with some tests first to see how he fought off the disease). Amy's like, get to the point: when do I become one of you? As Alan and Jules lock eyes, Jules says absently that Amy's body's adjustment to the fetus will let her absorb its Immortal juices, or something -- at this point, we think Jules is probably BSing Amy to buy time -- and Winger tells Alan he'll have to distill the red sap to a vaccine off the island; she's calling for an evac, stat.
Alan and Jules meet up in a hallway. What's he doing there? Looking for her -- but she's "been busy" with her "new friends at Ilaria," he sighs. The ones he's been stalking and blowing up? Alan's like, you told me to find you, what'd you expect. Jules admits that's true, then changes the subject to Ilaria's Narvikocide plan. Alan doesn't see how the slow death of humanity is really better than killing everyone at once. Jules says angrily that he can help her, or get out of her way. Or what, he asks? What happened to the Jules he fell in love with? "She became Immortal," Jules non-answers, walking away.
Amy's sent two redshirts (or, we guess, "brownrobes") to deal with Landry and Balleseros's bodies. Too bad for them, Landry's body isn't dead; he clocks the day players with a shovel.
Sarah's in her room, livid, and not trying to hear Jules's argument that giving Amy Immortality is the only way to save the world; she thinks Jules is trying to undermine the Immortaletus because it's Alan's baby. Jules shrugs that maybe gestating Immie in a mortal woman will give it a chance to grow, which it didn't do in Sarah's womb.
Kyle wriggles against his restraints as Winger tries and fails to get a sat phone signal. Alan comes in warning of the Narvik outbreak barreling towards them in two days' time; Winger says her superiors' comm links are down, but trails off, possibly thinking that said superiors aren't answering because they're in on the Narvikocide plan. Cut to Alan and Winger looking at a naval blockade through binoculars -- and it's not a rescue op. "They're going to kill everything," Winger breathes.
Alan demands an explanation. Winger's isn't comforting: the military's Plan A is "aggressive containment," but that having failed, it's time for Plan B, "eradication." They'll drop the X-Gas we saw earlier on the island and kill it. Alan starts packing up, thinking evacuation is still an option; it isn't. Alan's determined to synthesize a cure in the six hours remaining before the planes drop their death bombs. Winger's team can find them a bunker, then they'll hail the Navy "somehow" and get out of this jam.
Peter pulls rank on Kyle's guard in his smoothest Michael voice and examines the quarantined Kyle while purring about Alan's responsibility in everything that's happened to Kyle since he's come to Killigan's Island. Kyle growls that he was sent there to stop Alan, after which Peter stealthily loosens Kyle's wrist ties.
Anne visits Amy, who congratulates Anne on her impending grandmotherhood. Anne ignores Amy's you-jus-jellus taunts; she's giving Amy a chance to apologize for ruining so many lives. Predictably, Amy laughs in her face. She was given a chance, Anne says serenely.
Jules and Sarah regard Balleseros's body. Sarah blames Amy as Jules divests the corpse of the gun, then asks Jules why they can't just take the root. It's hidden, Jules says; they'll have to go through with the procedure to get it. We disagree, since Amy 1) stinks at hiding stuff (see: Immie's Cabinet O' Obviousness) and 2) stinks in general and will probably just screw them over in the end.
Alan takes Soren's blood and explains why he needs to test it. Soren's psyched to hear his blood is "very special" and to help manufacture the cure ... and to see Olivia, who comes in, embraces him, and says she owes Alan. Meanwhile, Kyle's attacking the guy who brought his lunch, and when said guy comes to, Peter's informs him that his "path ends here" and stabs him a gazillion times. Nice "leadership," freakshow. Anne finds him later in the chapel, bloodied and cradling the newborn, and asks if he's okay. He's fine; "it's done"; is she ready? More than ready. "This should be over by nightfall," he says, kissing her forehead. Meanwhile, Landry's lurking in the balcony.
Alan and Winger's team find Kyle's guard's body strung up, eyes gouged out, guts pulled loose. Alan smells a rat: this isn't the work of a mycotic, it's too "surgical." A Coast Guarder reports Peter came to see Kyle, but Winger dismisses Alan's claim that Kyle didn't do it and tells her team to shoot Kyle on sight. After they've gone, Anne comes in, thanks the dead man for his "sacrifice" and pulls a hazmat suit out of one of the backpacks on the table.
Jules and Sarah ready Amy for the implantation. Amy takes Sarah's hand: "Don't worry; I'll be a good mother." Sarah yanks her hand away. Amy warns them once more that they'll never find Mother without her before going under. Sarah's over it and lunges at Amy with a scalpel, but Jules ninja-blocks her millimeters from Amy's jugular. Sarah whines that Jules isn't a mom and doesn't get it. Jules needs Sarah to trust her.
Anne coaxes Landry out of his hiding place, though her attempts to turn him against Amy get her throttled and almost pitched over the balcony.
Amy herself is looking in a mirror post-procedure at her new silver eyes. She sobs with joy. Sarah stalks away.
Peter runs into Alan, who's hilariously dismissive of Peter's power-grabbing, but Peter successfully baits him into meeting with Jules at the botany lab, then walks off whistling a tune from South Pacific as Soren sneaks out to follow Alan. Hope he catches up fast, as Krazy Kyle drops a noose over Alan in the botany lab and winches him up on tiptoe, then comes down to ask why, if Alan's really there to stop the worldwide conspiracy, he didn't just kill Michael. "Ilaria," Alan gasps. Krazy Kyle accuses him of helping Michael develop the fungus as a bioweapon. Alan denies this, but Kyle's going to watch him die and then eat his eyes. Soren, eavesdropping, scampers off for help. Or to get popcorn, but we hope it's the first thing.
Amy is blathering about how she'd never hide the "glorious silver eyes" of her Immortality; Jules interrupts to say it's time for Amy to do her part. Amy stalls until Jules puts a scalpel to her throat: "Just because you're Immortal doesn't mean you can't die." Thank goodness for that. Amy says Mother's in a hollow stump north of the main gate.
As Soren loads a syringe with red-sap antidote, then plunges it into Krazy Kyle's leg, Winger's team seals off the Abbey as the X-Gas planes approach Killigan's Island. Winger calls for everyone to put on suits and masks. Gas falls over the island as Soren saws frantically at Alan's rope. "Somewhere Over The Rainbow" provides the creepy accompaniment to Jules dashing towards the stump and Amy dancing in a gas cloud, talking to "Father." Winger and her team, trapped outside, choke and begin to burn; Peter watches Winger through a door but does nothing to help her. Jules finds Mother. Soren gets Alan cut down. Amy's skin begins to boil and her silver eyes fade as we flash back to Sarah injecting Amy's eyes with silver dye. Ha! Nice. As she screams, "YOU CHEATED MEEEE," Sarah watches from a window.
In the aftermath, Peter surveys the wasteland outside and Anne tells him he saved the Abbey. Now it's time to finish the job. She hands him a hatchet, and he starts dragging bodies inside, including Amy, who is, to our dismay, too mean to die; she's coughing weakly. A gasping Alan admires Soren's smarts in saving him and they exchange smiling "You're on a good path"s as Jules approaches the Abbey gate. She stumbles just outside the door, and when Sarah comes out to see if she found Mother, Jules shows her Mother, dried out by the gas. She's dead -- and soon the rest of the world will be, too.