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.
Sarah's hunt for answers is interrupted by a trip to the suburbs. Alison's paranoia has boiled over, putting all the Orphans at risk. But when a party of suburbanites arrives on Alison's doorstep, it falls to Sarah to protect Alison from her neighbours' suspicions.
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 last chance to bring her nemesis back to sanity slips away as Art intervenes to get answers of his own. Meanwhile, the Orphans must decide whether to make peace with their creators, as Sarah is forced into a deadly confrontation with their enemy.
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.
