Castor pursues the Leda clones for original tissue samples. Helena, who is pregnant and imprisoned, is examined by a mysterious new villain. The Castor boys are also out to play, toying with a frightened young woman, Patty, in a sexy switcheroo that ultimately sets Sarah – and Art – hot on the Castor trail. But it’s not all fun and games for the Castor boys, as Sarah gleans they may have a mysterious defect that puts their lives in peril.
Rudy and a young woman, Pattie, enter a hotel room. They laugh and begin making love. At some point, another Castor clone comes in and joins in, Rudy introduces him as Seth; he's the one who helped Rudy escape. Pattie is upset by this, she hadn't planned on sharing, but Rudy says, we're brothers, so we share.
Cal leads Sarah and Kira to a place in the city, which turns out to be an apartment that Cal has bought, well furnished and equipped. He assures Kira that this is "our" house now, and tells Sarah that he can afford it. Both Sarah and Kira like it.
Rudy and Seth are in their apartment together, and Paul visits them; they address him as "Major" and, sometimes, act subordinate to him. Rudy complains that he saw Sarah Manning at Dyad. Paul tests both of them with an instrument involving a camera focused on an eyeball, and cryptic logic questions; Rudy does fine, but Seth shows discomfort, visual flashes, hand spasms. (As will be seen later, this is a diagnostic test for a neurological problem that Castor's are prone to.) Paul hands them envelopes, giving their orders for extraction from the situation, and return to base, though Rudy objects their work here isn't done.
Scott visits Cosima at Felix's place, and says her blood tests are doing real well, they are both surprised that she's had this much improvement just from the second treatment from Kira's tooth (it was expected to only let her survive until the blood marrow treatment). Scott says Dr. Nealon wants to meet with them, he's a great researcher. Felix hands Cosima a new pale blue clone phone; it's time to retire the green ones.
Alison and Donnie are at a soccer tournament, and they see Marci doing a campaign interview. Alison is sure she can beat Marci, but Donnie is worried about their finances, since he has no income. Ramon, Alison's drug supplier, comes over; Alison is surprised he's at a kids' sports tournament, but he says, half his clients are soccer moms, though he's working on getting out of the business to go to college. He congratulates Alison on staying clean. After he leaves, Alison tells Donnie they have a money-making opportunity.
Art calls Sarah, and tells her of the incident with Pattie and the two young men, that Sarah can recognize as Rudy and Seth. Sarah wants to talk to her.
At a military camp somewhere, Helena is wrestled into a room with soldiers, at least one of which is a Castor. Supervised by a doctor, she is given a round of waterboarding, until a middle-aged woman, Dr. Virginia Coady, comes in and orders a stop: Helena's blood test shows she's pregnant. By the respect she is given, Dr. Coady seems to be in charge.
Mrs. S looks battered and bruised, and Felix is with her. She fears that she's lost Sarah's confidence, and lost Kira, and has failed to keep Kira safe. Felix gives her a new clone phone and encourages her to scheme with her associates and do something to help.
Cosima and Scott meet Dr. Nealon at Dyad, and they agree, Cosima is doing well, but Scott wants to know if the original genome is still around. Dr. Nealon insists the data, and any samples, are gone, thanks to the Duncans, they had donors for two clone lines, male and female, and they're all gone.
Sarah comes to the police station, and Art says it's not safe for her to be there, but he tolerates her asking Pattie a few questions about Rudy and Seth. Pattie says that, after sex, they went through her ID, and copied information about her in a little notebook, and put a piece of her hair in a bag, and she has no idea what all that was for. Art tells her, if they can be found, they'll be charged with assault, at least, though she says it wasn't rape. Pattie says they also had the same tattoo on the left forearm, a picture of a two-headed horse.
Ramon meets Alison and Donnie in the soccer field support building, and Alison offers to buy Ramon's entire business, inventory, client list, everything, he'll be clear and can go do whatever he wants. Ramon asks if they have the "stones" for this work, and Alison and Donnie say they do (Donnie a bit too enthusiastically). Alison comments, most of his clients are already in her circle.
Seth is walking around, having flashes of vision, erratic behaviour, and gets a call from Rudy. They should be at the pickup location, but Rudy says he's not going back to base. Rudy knows Seth has been "glitching", the last week or two, and Seth says "it's" getting worse. Rudy plans to finish their job: he is breaking into Felix's loft.
From her lab, Cosima phones Sarah, and explains the two-headed horse tattoo: it's a play on the Castor of myth, who was a warrior horseman.
Helena is being given the Castor neurological test, but not cooperating at all. One of the soldiers, the Castor clone, tells her to obey, and she says, she's met one of his kind. Dr. Coady comes in and stops the test, taking Helena out for a walk. It's a desert colored base, troops all around guarding, even machine gun nests. Helena asks about the "Mark-faced boys", and Dr. Coady says she's had them since they were young, they call her "Mother". She impresses on Helena that Sarah and her family sold her out, they consider her expendable, but she's not expendable to Dr. Coady and her boys.
Sarah visits Mrs. S at her house, though Felix warns, she has broken ribs and possibly a concussion. Sarah wants to get in touch with Paul, but Mrs. S has no contact with him. She tells Sarah, it's no good trying to pretend she can have a life here, with Cal and Kira; they don't know what their enemies are, or what they want, and when that happens, Mrs. S had learned earlier in life, you don't fight, you run.
Ramon shows Alison and Donnie the drug inventory in his car; he estimates a street value of $80,000, but the cost to him was $25,000, and he also has goodwill worth paying for. Alison offers $32,000 for everything, including client list, in cash; eventually Ramon agrees. Aside, Donnie says they don't have that kind of money, but Alison says they do in their retirement money, and besides, this is her constituent list, her voter base, and she expects them to be very loyal supporters. They make the trade with Ramon.
Cal is unpacking dishes at the new apartment, and Paul visits him; Paul wants to know what Sarah was doing at Dyad, but Cal doesn't know either. Paul is surprised to see Cal settling down, as rich as he is, he got a lot from selling his weapons company. Anyway, the deal Paul made regarding Helena was to allow Sarah to get away, and now's the time for her to do so, Cal needs to convince her to get out of here.
Sarah and Kira arrive at Felix's, and they are both happy with the idea of living at Cal's new apartment. They discover Rudy, who threatens Kira to get answers out of Sarah. He wants the tissue samples of the Castor original that Ethan Duncan must have had, but Sarah knows nothing about it.
Downstairs from Felix's, Cal comes in after Sarah, and finds Seth there, guarding. Seth is having a lot of trouble with flashes and spasms, but tries to keep Cal from going upstairs where Rudy is. Seth's troubles dissolve into babbling, and then collapsing and yelling, which brings Rudy down from upstairs, leaving Sarah and Kira behind. Rudy sees how bad Seth has gotten, and shoots him, comforting him until he dies. Rudy leaves.
At Mrs. S's house, Cal and Kira pack to leave, they are going to Iceland (where Cal had said he had contacts). Mrs. S tells Cal her people will get him out of the country, and not to contact his people until then. Cal and Kira say goodbye to Sarah and leave. Sarah says, now we find Mark, he can lead us to Helena.
Mark and Gracie are staying in a motel somewhere, and Mark is in the bathroom. While biting on a washcloth, he uses a torch to burn away his two-headed horse tattoo.