Desperate to get off the island and reunite with her family, a wounded Sarah journeys into the island's interior, only to discover a mysterious village - the beating heart of the Neolution agenda.
Dragged home from the Island by Neolution, Sarah refuses to go along with Rachel's new regime. With the help of an erstwhile ally, Sarah sets a plan in motion to get her and her daughter out of Neolution's reach for good.
As Clone Club reels from the loss of one of their own, Sarah gnaws at the shackles Rachel has firmly placed around her family. Alison struggles to find her place in the sisterhood as the familiar trappings of Bailey Downs become increasingly, unfamiliar.
Sarah and Siobhan follow a lead on a Neolution defector, hoping for enough leverage to free Kira from Dyad's clutches. Meanwhile, on the island, Cosima investigates rumours about a mysterious creature in the woods.
While Sarah and Kira spend some well-needed bonding time at home, Cosima unlocks the island's biggest secret, discovering a startling connection between the village's so-called creature and the science around Kira.
Cosima is forced into an alliance with Susan Duncan when an old enemy returns to the Island, accelerating PT Westmorland's sinister agenda. Meanwhile, on the mainland, Krystal stumbles onto a vital clue to the Neolution endgame.