Sarah, a streetwise hustler on the run from a lifetime of bad decisions, witnesses the suicide of a stranger who looks just like her. Sarah assumes her identity, hoping that cleaning out the dead woman’s bank account will solve all of her problems. Instead, the street smart chameleon is thrust headlong into a kaleidoscopic mystery. After taking on the new identity, Sarah quickly finds herself caught in the middle of a deadly conspiracy and must race to find answers.

When terrifying evidence suggests the Orphans are part of a sinister ongoing experiment, Sarah’s suspicions turn to Paul, Beth’s boyfriend. But her probing inadvertently triggers Paul’s own investigation, bringing him dangerously close to the truth. Meanwhile, paranoid Alison piles on a whole new level of complication.

With Paul missing, Sarah is forced to confront the conspiracy head on. But when Paul learns Sarah has kept essential information from him, the fragile trust between them threatens to shatter. Meanwhile, Cosima grows closer to Delphine and the dangerously fascinating Dr. Leekie.

Sarah's actions pit the Orphans against each other as she tries to plan her next move. As Paul tries desperately to cover up Sarah’s existence, Alison takes vengeance on her suspected monitor, which could cost her everything she holds dear.

After Kira’s life is threatened, Sarah is on the warpath, but Dr. Leekie makes her think twice about her plans for revenge. Meanwhile, Cosima faces the truth about Delphine, forcing her to choose sides. Now, it’s up to Sarah to decide the killer’s fate, but the truth about where Sarah came from changes everything.

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.

Mrs. S orders the sisters to take a night off from sleuthing to celebrate Felix's art opening. But while Felix attempts to impress a famous gallerist with the help of his sestras, Sarah remains on edge with a nagging suspicion that S is hiding something. Meanwhile, wounded and desperate, Rachel reunites with an old ally, but their plans for revenge on Neolution put Clone Club in the line of fire.

With Helena forced to take shelter behind enemy lines, it’s a bloody last stand for survival as Sarah and Art struggle to protect her, and end the siege on the sestras once and for all.