In search of an anonymous whistleblower known as Thomas Shaw, CIA officer Daniel Miller travels to Berlin. Once there, Daniel reconnects with an old friend, and Shaw acts out violently as the net closes in.

Station Chief Steven Frost, with agents Robert Kirsch and Valerie Edwards, investigates an Islamic radical, attempting to stop an extraordinary rendition. Daniel looks into the death of Shaw's courier.

Langley investigators sweep Berlin Station, while Frost and Robert worry their secrets will be revealed. Hector compromises the hunt for Shaw, and surveillance brings attention to an agent's bad behaviour.

Daniel grapples with memories of the beginning of his friendship with Hector and his first posting in Chechnya. Frost positions himself for promotion, undermining his deputy in the process.

The station discovers the subject of Shaw's next leak is Chinese defector Houjin Lin, which aligns American and German interests. Daniel works with Esther Krug to counter Shaw's attack by getting Lin out of the country.

A joint sting operation, involving CIA officer Clare Itani, brings Valerie's investigation into Aleksandre and Ruth Iosava to a head. Things go from bad to worse with Langley's unannounced participation.