Betrayal tells the story of the German-Dutch Ludwig Mengelberg, an officer in the German army who holds the nickname of 'Der Fliegende Holländer'. Mengelberg finds it increasingly difficult to cope with the horrors of the war and when his wife and daughter are killed in a bombing, he makes a drastic decision. When he is transferred to the Netherlands, he decides to help a Dutch farm family covering up people in hiding. In doing so, he commits high treason against his own men. When the SS becomes suspicious and the resistance advances, Mengelberg not only puts his own life in danger, but also those of the people he aims to help.