Sarah pursues Helena, who is being held in a compound far away; Sarah must deter a Topside investigator.
Helena takes shelter behind enemy lines, and Sarah and Art struggle to protect her and end the siege.
Castor pursues the clones in order to obtain original tissue samples; Helena is examined by a new villain.
Westmoreland demands a more aggressive action on Kira; Sarah fights to save her daughter; Rachel discovers a dark secret; Cosima has a clue about Westmoreland's identity.
Helena works in a faraway military compound; Sarah's fate hangs in the balance as she tries to save her sister.
