Season 3 follows the fortunes of a young U-boat crew as they engage in the Battle of the Atlantic, are hunted down by an obsessed Royal Navy Commander (Ray Stevenson) and are sent on a dangerous mission to the Southern Hemisphere. Together they form strong personal alliances under the command of Robert Ehrenberg (Franz Dinda). And yet Ehrenberg&#39;s thoughts remain in Kiel, where he has developed feelings for Greta (Elisa Schlott). The young mother is married to a man who is seriously injured and suffering from war neurosis. Also in Kiel, Wilhelm Hoffmann's daughter Hannie (Luise Wolfram) is trapped in a loveless marriage to Commander Albrecht Lessing (Florian Panzner), a bitter, emotionally distant man. Hannie suffers under the tight constraints of her status and the social expectations that go with it. When she meets the charming submarine commander Schulz (Pierre Kiwitt), she is playing with fire. Meanwhile in the exotic climes of neutral Lisbon where the exiles, spies and criminals of Europe rub shoulders with each other and their enemies, Hagen Forster (Tom Wlaschiha) discovers a lethal plot to steal a fortune in plundered war time gold. These discoveries and aspects of his own history deriving from dark experiences on the Eastern front, lead him to question his own actions and moral path. They also lead him to a shadowy figure caught up in a conspiracy that might change the course of the War - for the better. That man, very much changed by his own shattering experiences, is Klaus Hoffmann (Rick Okon). These two historically based strands come together in an unexpected,  thrilling finale.！