A young woman's life changes dramatically after she assumes the life of a dead woman who looked exactly like her, and discovers that they are both clones.

Desperately searching for her daughter, Sarah and her clone sisters face a new challenge when they learn that one of their own is one of the orchestrators of the Neolution project.

The clone sisters must rely on one another to survive from the new threat of Project Castor, who are searching for an original tissue sample to solve a genetic flaw. Alison decides to run for the local school board.

Sarah reluctantly returns home from hiding to track down an elusive potential ally with ties to Beth Childs, and is drawn into a mystery that threatens to pull her and her sisters apart.

Under the heel of Rachel and Neolution, Sarah and her sestras must change their tactics if they are going to protect the ones they love and finally free themselves from those seeking to control their lives.

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