With an ailing Sarah being held by Castor, Paul tries to get to the bottom of Dr. Coady's illicit experiments. Delphine returns with questions about Cosima's work, and Donnie and Alison approach Jason Kellerman about taking their business to the "next level." Meanwhile, Felix confronts Rachel for information about Sarah's location.
U.S. air dates are in MM.DD.YY form. U.K. air dates are in DD.MM.YY form.