Sarah Manning, a street-smart grifter and orphan, witnesses the suicide of a woman who looks exactly like her:
police detective Beth Childs. Desperate to escape a turbulent life and provide for her daughter, Kira, Sarah assumes Beth’s identity. However, she soon discovers that she is not an individual, but a clone—one of many "Project Leda" subjects scattered across North America and Europe. As Sarah delves deeper into the mystery, she encounters her genetic sisters, each with distinct personalities: the suburban soccer mom Alison Hendrix, the brilliant scientist Cosima Niehaus, and the unstable, murderous Helena.United by their shared origins, the sisters form a fragile sisterhood while navigating a treacherous web of conspiracies. They are hunted by the Neolutionists, a shadowy scientific movement obsessed with human directed evolution, and the Proletheans, religious zealots who view the clones as abominations. Sarah’s primary motivation remains protecting Kira, who possesses a mysterious ability to heal rapidly, making her a target for those seeking to exploit the clones' genetic code for corporate and political power.The narrative expands as the clones uncover the existence of "Project Castor," a parallel program of male clones raised in a military environment, suffering from a lethal neurological defect. The sisters must constantly balance their personal lives—Alison’s marriage, Cosima’s illness, and Sarah’s struggle for autonomy—with the relentless pressure of government surveillance and
corporate greed. Their journey is a harrowing exploration of bodily autonomy, the ethics of human cloning, and the nature of identity.As they peel back the layers of their creation, they realize that the Dyad Institute and the mysterious Topside organization have been monitoring their every move since childhood. The conflict culminates in a desperate battle against Susan Duncan, the original architect of the Leda project, and the manipulative P.T. Westmoreland. Through betrayal, loss, and profound sacrifice, the sisters evolve from mere biological experiments into a formidable force of nature. Ultimately, Sarah and her "sestras" fight not just to survive, but to reclaim their lives, proving that while their DNA may be identical, their souls and choices are entirely their own.