One year after the emergence of worldwide Synth consciousness tensions run high between humans and Synths, as Max tries to hold his people together inside their Railyard settlement. Laura considers a new path in fighting for Synth rights after a terrorist bombing ruptures a fragile peace.
Max's leadership grows tenuous when Agnes challenges him, as Mattie helps Leo re-acclimate. Laura is uncertain about her new role on a government commission to decide the fate of Synths in the U.K. While Niska and Mia go in search of a group of Synth refugees, Karen helps Sam pass for a human boy amidst an unsuspecting community.
Growing frustrated with her place on the Commission, Laura tries to get closer to Dr. Sommers -- while Mia hopes to prove to a human neighborhood that peaceful integration is possible. Niska receives an unsettling message, and Joe offers to help Sam blend in.
Max prepares for the Dryden Commission's visit to the Railyard, hoping to show them that coexistence is possible -- though it puts him at odds with Agnes. Mia comes face to face with the man who betrayed her, while Niska's investigation leads her to the bomber.
Joe brings Sam to the Hawkins home, hoping to help him recover from a major trauma at Waltringham, while Laura and the Synths are encouraged by a small legal victory. Max's recent decisions undermine his leadership, and Mattie makes a new friend at school.
As Leo returns to his childhood home, Laura discovers that someone close to her is plotting something terrible -- putting her family's lives at risk. Niska finds a man who says he can take her to the Synth who sleeps, and Max discovers his betrayer.
After another Synth attack Max is forced to confront Anatole at the Railyard, while Laura hopes to right a wrong by discovering the truth about Operation Basswood. Niska finds a broken Synth was a message about the hilltop, and Leo enters the lion's den.
As the Dryden Commission executes Operation Basswood, Mia rushes to the Railyard to try and save the lives of her friends -- though the violent conflict with humans is now inevitable. In the forest Niska encounters a unique Synth with a message about the future, and Mattie faces a monumental decision.
