During Siobhan's funeral, Sarah gets word that Helena is being held captive and rallies her group to try to save her. Helena considers making a sacrifice play to avoid her children from being experimented on.
This episode contains examples of:
- The Bait: Sarah plans to play this role, by showing up as Rachel and distracting John into a Motive Rant. The part where Art tracks her back to the place where the remaining Neolutionists are holed up works pretty well; the distraction part, not so much.
- Bald of Evil: John's hair is actually a wig, showing how much in dire straits he truly is in.
- Bavarian Fire Drill: Scott and Hell Wizard get through the police cordon around Dyad by carrying a cooler and repeatedly uttering the words "pediatric heart transplant".
- Big Eater: Young Helena is not immune to her older self's big appetite, stealing candy from a nun's drawer before the nun comes in wanting to masturbate.
- The Bus Came Back: Tomas returns in a flashback, having been killed off in Season 2.
- But Now I Must Go: Felix reads a letter written by Siobhan that she penned in the previous episode before the plot to expose Neolution was in full swing.
- Call-Back: The Prolethean dagger that Helena uses returns here.
- Can't Kill You, Still Need You: John is quite pissed off Sarah (dressed as Rachel) for attacking him and is ready to finish her off, when Dr. Coady bursts in saying that Helena needs blood, lots of blood, and as her identical twin, Sarah can provide this via a transfusion.
- Chekhov's Gun: The Castor Pathogen is mentioned here, and its role is finally confirmed: to be mass produced and put in creams from Len Sipps's company.
- The Coroner Doth Protest Too Much: Most of the Neolution board members are dead of "suicide". It's not clear how many of them are actual suicides, but given that John explicitly sent Frontenac to murder Al-Qatib, at least some of them probably fall under this trope.
- Curb-Stomp Battle: Dr. Coady gets too close to Helena while she is in labour, allowing Helena to use Dr. Coady's head as a basketball against the bedrail.
- A Day in the Limelight: This is essentially Helena's episode.
- Disproportionate Retribution: The nun does this to Helena when the latter catches nun masturbating. The nun proceeds to dunk Helena's head in bleach, which explains her bleached hair, and red eyes.
- Driven to Suicide: Helena attempts to shield her children from experimentation by deciding to commit suicide by slicing her wrists with a pair of scissors. It doesn't work, as Dr. Coady is able to save her before she loses too much blood.
- Due to the Dead: Subverted by Cosima and Alison given that only Sarah is able to go to Mrs. S's funeral.
- Even Evil Has Standards: Dr. Coady is disturbed that Maddie Enger executed Gracie in the prior episode and also does not want to kill Mark Rollins when John insists. She eventually relents and gives Mark a lethal injection, but is clearly disturbed in doing so.
- Exact Words: When Mark asks when he can see Gracie again (not knowing that Maddie executed her in the previous episode), Dr. Coady responds by saying that she will be there when he wakes up. Just not in this life.
- Hidden in Plain Sight: No one figured out that Helena was being held at an old wing at the Dyad institute.
- Oh, Crap!: Helena when her water breaks.
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The Other Darrin: Young Helena is played by a different actress and not Cynthia Galant (who has earlier played young Rachel as well as Charlotte). Word of God handwaved this by saying the Helena in this episode is meant as a flashback to a younger age. - Out-of-Character Alert: John gets suspicious of Sarah pretending to be Rachel when she calls him "father", something Rachel had never done.
- Pregnant Badass: Despite suffering blood loss and actively undergoing labor contractions, Helena still has enough strength to beat Dr. Coady's skull into a bloodied mess. Still alive though.
- The Reveal: This episode finally reveals the true intents of the Neolution Movement. John wants to create a serum that would allow people (namely those in the upper class) to permanently reverse any form of cell damage and confer a person immunity from any disease. As for the rest? They would likely be sterilised by the Castor pathogen using the creams from the company purchased from Len Sipps.
- Running Gag: Continuing on a plot point from Season 3, Rachel isn't too happy to see Scott again.
- Start of Darkness: We see the abuse that Helena suffered before she was turned over to Tomas where she became a brutal assassin.
- Tracking Device: On the car with Sarah in the trunk.
- Twin Switch: Sarah decides to have Rachel given up to Neolution given that there is likely a price on her head. But it's not Rachel, but Sarah, as John figures out pretty quickly.
- What Happened to the Mouse?: Despite the Proletheans making a return here, their exact relationship with Neolution is still not explained. Not only that, we don't see Henrik Johannsen, or any mention of why Tomas followed a path different than Johannsen.
- You Have Outlived Your Usefulness:
- John orders Dr. Coady to dispose of Mark Rollins as they already have isolated the Castor Pathogen for their own ends.
- Various board members of Neolution are given this as John tries to cover up his tracks as much as he can.
