Sarah joins forces with an unlikely and untrustworthy ally, following a trail of clues that she hopes will lead her to the origins of the clone experiment. Cosima and Delphine make a discovery that could prove to be the key to treating her illness. Alison finds herself in unsavory company at rehab.

When a rehab confidante betrays Alison and threatens to expose the truth about Aynsley’s death, she goes into free fall on the eve of Family Day. With Donnie and the kids set to visit, it’s all clones on deck to contain the fallout.

A new player in the clone conspiracy turns up at Felix’s door, sending him into crisis mode. With Cosima running out of options, Sarah struggles with the decision to surrender a crucial piece of leverage and make a deal with Dyad.

Cosima takes a turn for the worse, forcing Sarah to take desperate action which results in tragic consequences for those she loves. The Proletheans set their ultimate plan in motion, while Alison and Donnie tangle with the law.

The war with Dyad is all but lost when Rachel’s latest ploy forces a broken Sarah to concede. The Clone Club springs into action, uniting in a reckless gambit to save Sarah. As they fight to gain their freedom, Sarah encounters a new ally and uncovers a terrifying new dimension to the conspiracy.

Castor and Topside force Sarah to make uneasy alliances. But there is some rest for the wicked, when Donnie gives Helena an unexpected ‘gift’, and the results of Alison’s candidacy finally come in. Even as team Leda takes a moment to breathe, change is afoot and a life hangs in the balance.