Humans

As the Hawkins family struggle to put past events behind them, a visitor arrives unannounced on their doorstep. Living as a fugitive in Berlin, Niska faces a critical decision, while in the UK Mia, Leo and Max hide out on the coast. In San Francisco, Athena Morrow, a fiercely-driven AI scientist is recruited by Milo Khoury, a renowned entrepreneur, for a top-secret project.

Laura must decide whether to accept Niska's request, while Karen and Pete learn about a special synth being sold for unprecedented amounts on the black market. Hester uses questionable means to gain information from their prisoner, and Leo faces a new mission. Mia takes a risk to help Ed but is her secret now in jeopardy?

Athena travels to the UK and her tragic secret is revealed. Niska's consciousness assessments begin. With more time at home Joe notices Sophie's increasingly eccentric behaviour. As Karen returns to work with Pete, cracks start appearing in their relationship. The synths are forced to leave their hideout but Mia shocks them with a huge decision.

Mia and Ed get closer but their relationship is thrown into jeopardy when their secret is discovered. Toby gets closer to Renie but offends her when he attempts to break through her synthie mask. Things are looking 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 a massive risk. Odi struggles to find meaning, while Sophie is awestruck by Renie's 'synthie' lifestyle. As Pete recovers from his assault, Karen makes an admission which rocks their relationship.

Athena challenges Milo's ethics and is shocked when he reveals his real plan. Mia's surprise return has ramifications for the Hawkins family. Mattie finds Leo but can she trust him with her secret? Max resolves to begin a new community of synths; when he learns how far Leo is prepared to go to complete his mission, he takes matters into his own hands.

When Mattie reveals that the synths are planning to break into the Silo, Laura determines to find Niska and ask for her help. Mattie asks for Max's help to save Leo from Hester's influence. Toby receives a disturbing message from Renie. Karen seeks out Athena's help and makes a life-altering decision. Mia and Hester break into the Silo but things don't go according to plan.

In the aftermath of the Silo tragedy, Karen feels her and Sam have no future and takes matters into her own hands. Niska and Astrid prepare to return to Berlin, but can Niska really walk away from her family? Joe leaves Laura shell-shocked with a frank admission. Hester seeks revenge and will stop at nothing to hurt Leo.