After evading a Neolution attack in Iceland, Sarah returns home to track down an elusive new ally. As Cosima struggles with Delphine’s disappearance, Alison and Donnie host a pregnant and ever-hungry Helena. Meanwhile Felix, feeling like an outsider, embarks on his own journey of self-discovery.
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.
Sarah realizes her goals have aligned with a former enemy and forms a precarious alliance in hopes of getting to the head of Neolution. Alison heads a mission to infiltrate a Neolutionist fertility clinic that Beth investigated, and sends Donnie and Felix in undercover. Back at the lab, Cosima and Scott receive a special delivery from Alison. As Rachel grows closer to Charlotte, Susan leaves a devastating decision in Rachel’s hands. A desperate Sarah returns to Dizzy needing his help again.
Sarah regresses to old habits while struggling to cope with a loss. Following in Beth’s footsteps, Sarah questions her strength to carry on.
Andy weighs up an opportunity to leave town for several months on an undercover project, while Jarvis reveals some shocking news.