Niska is living as a fugitive in Berlin, while the other Synths are laying low in the UK.
Laura must decide whether to accept Niska's request, while Karen and Pete learn about a special Synth being sold on the black market.
Athena travels to the UK and her tragic secret is revealed. Niska's consciousness assessments begin, and the Synths are forced to leave their hideout.
Mia and Ed get closer but their relationship is jeopardised when their secret is discovered. Things look bleak for Niska until Laura brings in a surprise witness.
When Mia risks falling into the hands of a mysterious organisation, she is forced to take drastic action, while Sophie is awestruck by Renie's 'Synthie' lifestyle.
Athena challenges Milo's ethics and is shocked when he reveals his plan, while Mia's return has ramifications for the Hawkins family.
Mattie asks Max to help save Leo from Hester's influence. Toby receives a disturbing message from Renie, while Mia and Hester break into the Silo, but things don't go to plan.
In the aftermath of the Silo tragedy, Karen takes matters into her own hands. Can Niska leave her family? Joe leaves Laura shell-shocked, while Hester seeks revenge on Leo.
When fractures start to appear in the Synth community, all hope of stability comes under threat, and both families are brought back to fight for the Green-Eyes' survival.
A grieving Max must face the consequences of his painful decision. Laura discovers she's not being told everything at the Dryden Commission, while Joe uncovers Karen's shocking secret.
Laura struggles to uncover the truth about Operation Basswood, but a conversation with Sophie inspires a bold idea. Mattie and Leo confront their feelings for each other.
Laura leads a tense Dryden Commission on a visit to the Railyard, but will Agnes' anger threaten its success? Mia comes face to face with Ed, forcing her to confront her past.
While Sam reels from the events of Waltringham and Joe struggles to help him through it, truths are revealed and dangerous plans put into action at the Railyard.
Laura discovers a shocking truth that threatens her life and everyone around her. Niska continues on her mysterious journey, and must defy all her instincts to survive.
Laura reels from her heartbreaking decision. Niska's journey takes an unexpected turn. Leo races to be by Max's side but walks into danger.
In a dramatic showdown, humans and Synths go head-to-head. Will Mia and Max's peaceful protest cost them their lives? Laura, Niska and Mattie face major decisions.
