After evading a Neolution attack in Iceland, Sarah returns home to track down an elusive new ally. She follows breadcrumbs and uncovers the next facet of Neolution’s agenda – implanting dangerous technological devices in humans. However, those she left behind are wary about her return, not wanting to relinquish their semblance of normalcy. As Cosima struggles with Delphine’s disappearance, Alison and Donnie host a pregnant and ever-hungry Helena. Meanwhile Felix, feeling like an outsider, embarks on his own journey of self-discovery.
The safe house in Iceland is the scene of frenzied activity, as Sarah is in a hurry to get Kira, Siobhan, and Kendall ready to leave. The others aren't so sure that her urgency is justified, they're sure they've been careful, but all that changes when Kira sees lights in the distance, coming their way. They get in the truck and drive off, leaving the house burning behind them.
They settle into a new safe house back in Toronto, a basement underneath The Rabbit Hole Comics and Games, which the owner, "Hell Wizard", has outfitted to be both a safe residence, and a laboratory (mostly outfitted with equipment stolen from Dyad), all paid for by the Hendrix's. Kira wonders if Cal is going to join them there, and nobody will tell her anything about Cal. Cosima and Scott are already there, working, and Cosima is looking somewhat better, but not entirely.
By phone, the sisters discuss M.K. and her warning; none of them know M.K., but Cosima realizes her sheep mask is suggestive of the first clone, Dolly the sheep. Scott says Dyad seems out of the clone business, all the people they know are gone, perhaps meaning the running of the "clone experiment" is down to them. Cosima and Scott are working on the cure to the Leda problems, fueled by Kendall's genome. Sarah is sure M.K. knows things, so she should find her.
Art and Sarah discuss M.K., she had a Scandinavian accent, and was very paranoid. He passes her a file he has on guys found dead with one cheek cut out, often wearing one white contact lens, perhaps connected to Neolution. They don't know what Beth was up to with them, but Art has her townhouse key, they should check it out.
Alison visits Felix at his loft, the sisters have been worried that he hasn't been returning their calls. He says he's been busy (his loft has had lots of repainting done in a different style), and he's been working on "something" that Alison knows about, but he says it's not time to let the rest of the family in on it yet.
Art and Sarah find Beth and Paul's townhouse unoccupied, but with their belongings mostly boxed up; the rent is paid to the end of the year, so nothing has happened. They search. Sarah looks in the refrigerator...
Beth looks in the refrigerator, gets a beer, and offers one to Detective Martin Duko. She says she's not bothered by near-suspension, it's paid leave. He remarks on her book on Neolution, and on her attention on Dr. Leekie, but then he becomes serious: she keeps digging at this case she's been taken off of, and she and him have both crossed lines they can't go back over. He says he's going to do what he has to, protecting those he cares about. This sounds like a strong "stay out of it" signal.
Back in the present, Donnie and Helena go to the clinic for a pregnancy checkup, presenting Helena as Alison Hendrix (using Alison's health card, and explaining away the different hair). The nurse does an ultrasound on her, and it turns out Helena is expecting twins. Helena and Donnie are delighted.
Cosima does more work with Kendall's DNA, taking more blood samples as needed. Siobhan wonders if another treatment with Kira's stem cells would help, but Cosima says that's the wrong approach, she can't experiment on gene therapy if she's doing some other treatment.
Art and Sarah at the townhouse find Beth's hidden drug supplies, and then the camera Beth had placed in the living room, behind a painting. They find the recorder the camera was feeding, and copy the feed data.
They start watching the security camera footage, and see the scene in the last episode where Beth was pointing her gun at Paul. Art remarks that he knew Beth and Paul were having problems, but not this bad. Later on, the camera shows Trina visit, a woman with one white contact lens, so a Neolution follower. They figure Beth looked into Dr. Leekie, then met one of his disciples, and perhaps M.K. was steering her. Sarah takes a picture of Trina: she's going to find her.
Sarah picks up Felix and they go to Club Neolution. (She grumbles that Felix's phone has been off, he's out of contact.) He's there to get her in: she can't show her face at the door, so he'll let in in by the back door.
Donnie shares the news of Helena's twins with Alison, and their responses are night and day: Donnie is excited and supportive, and Alison sees Helena as a crazed, trained killer, who has been sponging off of them and making a mess of their house. Alison is mostly being frazzled with her own responsibilities.
Scott has blood test results for Kendall, and he's not happy about her white blood count, but she says she knows, it's leukemia, diagnosed months ago. She hasn't told Siobhan, and doesn't want her or anyone else to know, it would make everyone just pity her, and she doesn't want that.
Sarah goes through Club Neolution, full of modded people, loud music, branding and tattooing, showing Trina's picture. Felix isn't helping, he's just drinking, and she asks him why. At length, he reveals that he's been looking for his birth family, and waves off her assessment that she and Siobhan are all the family he needs.
Sarah meets a man called Dizzy who comes to her and calls her "M.K." (she is wearing a hood like M.K. always did). He complains that she's there early, she was supposed to meet him an hour later, but he has "it". He shows her a video he found, shot in Bogota two weeks ago; it shows a man getting a tiny worm pulled from inside his right cheek, but when they cut into it, something erupts from it, covering his face and killing him. Dizzy says he had heard rumors of Neos with implanted technology, perhaps gene-spliced, he doesn't know what it's for, only that "you" (M.K.) put him on to it. He then looks at her again, and asks who she is. They struggle, she steals his phone and runs off.
Outside, she looks in his phone, and finds the last text message: "MK CU @ Sudz & Tumble @ 12."
We see a flashback of Beth doing makeup, putting on a blond wig, and encouraging herself "You can do this". She goes to the living room, puts her gun in purse. and leaves. Then we see Art watching the last part of this in the security camera footage.
Sarah gets to the laundromat Sudz & Tumble, and Dizzy's phone rings. Sarah answers, and it's M.K. calling, who says Sarah shouldn't be here, it should be Dizzy. Sarah figures out that M.K. is watching via the laundromat's security camera. After Sarah puts her phones in a dryer, M.K. will answer questions: she found that "they" were coming to Iceland by searching a lot and finding her name and Kendall's. But M.K. won't talk more, "it will kill you, like it killed Beth."
Art, watching the security camera footage, sees Beth returning to her house,still in her blond wig, rushing in the door and slamming it, removing her wig. She is trembling and waving her gun.
In a flashback, Beth is trembling and waving her gun, there is blood all over her hands; she gets a drink, and finds M.K. standing there in the kitchen, she had come in by the back. Beth drinks more, then goes to the bathroom to wash the blood from her hands, and also to cut up a "Brightborn" ID card and flush it down the toilet. Coming out, M.K. asks how she can help, and Beth says there's nothing to do, it's over, we're done, she's screwed everything up. She gets her bag, tells M.K. to watch "the others" for me, and leaves.
M.K. continues explaining to Sarah, that was the last time she saw Beth, the night she killed herself. (By the way, half the time Beth, and some others, address M.K. as "Mika".) Beth wouldn't tell M.K. why she killed herself, but M.K. figures it had something to do with those worm-things, the "maggot-bots" M.K. calls them. M.K. says the only thing to do is hide, but Sarah says hiding doesn't work. Sarah looks outside, and sees that M.K. is sitting in a car; she pulls on her sheep mask and drives off.
As she does that, the white guy and black girl, Frank and Roxie, walk in, wearing their paramedic uniforms. They grab Sarah, get out a scalpel, set up an anaesthetic mask for her... and then look at her closely, and remark to each other "it's not her." Frank pries her mouth open, looks inside her cheek, says something to Roxie in Afrikaans, and they both look annoyed. They pack up their gear and go, leaving Sarah there, confused.
Sarah storms into the safe house under the comic store, outraged, she complains that, when Dyad had her, they did something to her. She tries to look in Kira's mouth for a bit, until Kira pulls away. She tells Siobhan: "I think there's something inside me, they have these implant things, and these Neos, they attacked me, and I think there's something in my jaw." She shines a flashlight in her mouth, Siobham examines her cheek from outside, and sees unusual lines. Siobham touches the cheek, and something moves, like a little worm.
- Tatiana Maslany as Sarah Manning/Beth Childs/Cosima Niehaus/Alison Hendrix/Helena/M.K.
- Jordan Gavaris as Felix Dawkins
- Kevin Hanchard as Arthur Bell
- Ari Millen as Ira
- Kristian Bruun as Donnie Hendrix
- Maria Doyle Kennedy as Siobhan Sadler
- Dylan Bruce as Paul Dierden
Special Guest Star
- Josh Vokey as Scott Smith
- Alison Steadman as Kendall Malone
- Skyler Wexler as Kira Manning
- Rosemary Dunsmore as Susan Duncan
- Joel Thomas Hynes as Dizzy
- Sarain Boylan as Astrid
- Gord Rand as Detective Martin Duko
- Julian Richings as Benjamin Kertland
- Ian Matthews as Frank
- Miranda Edwards as Roxie
- Allie MacDonald as Trina
- Ivan Wanis Ruiz as Alonzo Martinez
- Calwyn Shurgold as Hell Wizard
- Jonathan Purdon as Driver
- Colton Gobbo as Teenager
- Jay Walker as Club Kid
- Francisco Trujillo as Surgeon