Spymasters Sinclair and Faber face off: two world-class poker players gambling with human lives. Neil and Harry face a harrowing road trip to find Miri.
The team head on 2 different trains to Poland as Faber and his wife were posted there. The men from the team could only get passage without papers if they were on a prisoner train headed to a concentration camp.
While Aurora becomes involved with Heidi's resettlement scheme, Alfred and Neil must try to keep Faber alive after he is captured by the Polish resistance. Krystina isn't happy when Sinclair chooses new raw recruits.
Aurora struggles to keep her cover as Helene Bauer as the Nazis hunt for spies among the Polish resistance. Two new Camp X recruits join the team on a dangerous mission that brings them closer to the heart of Operation Marigold.
The team are in Berlin preparing to capture the scientist at the centre of Operation Marigold. Meanwhile Sinclair strikes a deal with Faber to get his son back, but all does not go as planned.
In the series finale, the team are in Berlin trying to shut down Operation Marigold. However, with Neil in custody and Faber's allegiance uncertain, can they prevail?