Sarah is out of options, on the run, and pursued by deadly adversaries. Desperate to find her daughter Kira, Sarah suspects ruthless pro-clone Rachel is behind her daughter’s disappearance and sparks an all out war against her. Alison and Donnie attend the funeral of her fallen friend, Aynsley, causing Alison to sink into guilt and despair. Cosima is faced with a perplexing decision that may have dire consequences.

While Alison struggles with Aynsley's death and Cosima grapples with the worsening symptoms of her mysterious sickness, Sarah enlists Art’s help to find Kira and is shocked when she learns where the trail leads.

After hitting the road with Felix, Sarah is forced to turn to a ghost from her past - an old flame named Cal Morrison. When their brief respite is brutally shattered, Sarah realizes that no matter how far she runs, it will never be far enough.

Sarah comes home looking for answers, and with the help of Cosima, they begin digging into the origins of the clone experiment. The hunt for answers takes her right into the belly of the beast, but getting out could cost her more than she knows.

Rachel goes on the warpath, lashing out at Sarah's nearest and dearest. While she tries to keep her loved ones safe, an unexpected visitor threatens to derail Sarah's plans.

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.

When the menace of Castor rears its head once more, Sarah and her entire family must come together to survive.

Castor pursues the Leda clones for original tissue samples. Helena, who is pregnant and imprisoned, is examined by a mysterious new villain. The Castor boys are also out to play, toying with a frightened young woman, Patty, in a sexy switcheroo that ultimately sets Sarah – and Art – hot on the Castor trail. But it’s not all fun and games for the Castor boys, as Sarah gleans they may have a mysterious defect that puts their lives in peril.

Leda and Castor are both on the hunt for original clone DNA. On-the-lam, Mark and Gracie pursue new leads to find the samples that might set them free, while Art and Sarah reunite to track them down. Meanwhile, Cosima and Scott try to learn more about Castor’s biology and Alison’s new money-making venture is going gangbusters. A shocking revelation about the Castor-Leda connection leaves the sisters reeling, just before Sarah witnesses a deadly Prolethean-Castor face-off.

Mark is taken down in a Prolethean shoot-out and Sarah must step in to help. But as Sarah gathers intel that puts her on the trail of the original Castor DNA, a familiar foe is not far behind. While Helena continues to toil in a faraway military compound, it is ultimately Sarah’s fate that will hang in the balance as she tries to save her sister. Meanwhile, Gracie is cast out from the Prolethean fold, and Alison and Donnie come face-to-face with unhappy drug lord, Jason Kellerman.

Helena and Sarah are reunited at the Castor camp. As Sarah suffers testing, Paul appears to chide her; but his allegiances are beginning to strain. While the Leda family worries about Sarah’s absence, Gracie ‘breaks loose’ under the care of Mrs. S and an unwilling Felix. Cosima falls hard for an internet date, Shay.

Paul digs and finds the ugly truth behind the Castor Boys’ logbooks of names, pushing him into action. Meanwhile, Felix is desperate for info on Sarah’s whereabouts, and presses the still-ailing Rachel for any shred of a lead. In order for Donnie and Alison to take their money-making endeavor to the “next level” she must introduce Jason Kellerman to her unique business plan.

Alison must secure a store front in order to take her and Donnie’s business to the “next level”. But things don’t go according to plan when her mother, Connie, proves to be a major hindrance. Cosima is facing familiar health issues and calls upon beleaguered Alison for a favor. But with Alison working to save an imperiled Donnie from the merciless hands of a drug lord, it’s Cosima who ends up doing a favor. An unassuming Scott gets closer to the greatest discovery of all, when he sits down with beleaguered clone Rachel.

When Rachel makes a promise to Sarah, it comes with a hefty price. Meanwhile, Helena and Gracie work with the Hendrixes, and Donnie takes Kellerman to task. Over at Castor, Coady and Benchman scheme to track down the Castor Original, and Rudy descends on DYAD for a much needed asset.

Sarah, Felix, and Mrs. S are in London to track down the Castor Original, but their enemies are not far behind.

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.

After two months of respite, Sarah’s hard-won refuge in Iceland is shattered by a Neolution attack. Once again forced to flee, she realizes no matter how far her family runs it will never be far enough.

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. 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 her once enemy and forms a precarious alliance in hopes of getting to the head of Neolution. Meanwhile, on her end, Alison dispatches Felix and Donnie to infiltrate a Neolution fertility clinic that Beth investigated. Back at the lab, Cosima and Scott receive a revolting delivery from Alison. As Rachel grows closer to Charlotte, Susan Duncan leaves a devastating decision in her hands.

Sarah’s day off to reconnect with Kira quickly turns into a sleuthing mission aimed squarely at discrediting Felix’s new ties. Cosima steps up with Donnie to further investigate the Neolutionist fertility research center. While Donnie bumps into an all too familiar face, Cosima makes a shocking discovery that leads her into a dangerous encounter.

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 Godderitch, from herself.

Sarah regresses to old habits while struggling to cope with the consequences of her decisions —reconnecting with Beth on a dark night of the soul. Back at the lab, Cosima, haunted by vicious memories and news of Delphine, attempts a dangerous Hail Mary to find a cure. At the Hendrixes, Alison is more determined than ever to create normalcy for her kids. As she forges ahead with a birthday party, Donnie is caught in the Neolution crosshairs.

As Alison is terrified by Neolution threats made against Donnie, Sarah and Mrs. S question her loyalty to her sisters. While Sarah is distracted, Siobhan sneaks out to seek vengeance. Meanwhile, Cosima and Susan Duncan work together in a final attempt to discover a cure.

With Susan Duncan deposed, Sarah finds herself in the same position as Rachel — under the heel of a new HBIC — causing the archenemies to come together for the greater good. Cosima and Susan butt heads on the ethical implications of human experiments. Meanwhile, when the Hendrixes' legal counsel, Adele, further investigates Donnie’s case, she begins to suspect Felix is keeping deep secrets. Helena’s arrival forces Felix to make a difficult decision.

When communication with Cosima is cut off and Neolution appears to be within striking distance, Sarah's alliance with Rachel goes out the window. Sarah lures a high-level Neolutionist into a trap, and sets out to bring down Neolution once and for all.