Sarah forms an alliance with a former enemy in hopes of getting to the head of Neolution. Elsewhere: Alison orders Felix and Donnie to invade a Neolution fertility clinic and a Susan Duncan leaves Rachel to make a devastating decision.

When Cosima admits doubts about finding a cure in time to save her life, Sarah makes a lone decision that exposes Kendall to those she's spent years hiding from. Meanwhile, Art and Felix team up to protect naïve clone, Krystal Goderitch, from herself.