The Stigmata of Progress (S04E03)

As Sarah reels from the shocking discovery of Neolution's biotech, she's desperate to find answers. Always impulsive, she follows a lead into a harrowing encounter that requires the help of a reluctant new player. Eager to assist, Mrs. S. strikes an alliance with an old nemesis. Rachel receives a visit from her keeper and takes a fraught step forward towards recovery. Meanwhile, Helena is mistaken for "Mrs. Hendrix" when she answers a visit from suspicious visitors. (BBC America)