Callum uses unorthodox methods in his attempts to convince Dieter to work with the British, while juggling the demands of Kathy, an officer in the War Crimes Unit, and his troubled younger brother, Victor.Kathy's team are concerned that the British government is harbouring war criminals under the name of science, while Victor struggles to deal with the psychological trauma caused by his experience of fighting the war. Kathy and Victor seek Callum's help, but can they trust that he will put their aims before his own?The power play between Dieter and Callum eventually puts Lotte at risk.