Sarah pursues Helena, who is being held in a compound far away; Sarah must deter a Topside investigator.
Leda and Castor hunt for the original clone DNA; Mark and Gracie pursue new leads; Art and Sarah reunite.
Castor pursues the clones in order to obtain original tissue samples; Helena is examined by a new villain.
Paul learns the truth about Coady's plans for Castor and has no choice but to make a dangerous play; Alison and Donnie hatch a plot of their own regarding Bubbles.
Helena works in a faraway military compound; Sarah's fate hangs in the balance as she tries to save her sister.
