Season Two
December 1942. We meet the very experienced U-boat ace Johannes von Reinhartz (Clemens Schick) who is sent with U-822 on a secret mission to the US East Coast in order to disembark three saboteurs. His loyalty is questioned and U-612, with its Commanding Officer Wrangel (Stefan Konarske), is sent in pursuit. Former U-612 Commanding Officer Hoffmann (Rick Okon) narrowly escaped death in the Atlantic Ocean. In New York he finds shelter with Sam Greenwood (Vincent Kartheiser), who owes his life to Hoffmann, and meets the sleazy German-born lawyer Berger (Thomas Kretschmann). Will he enable him to return to Germany? Back in La Rochelle, Simone (Vicky Krieps) is still secretly helping those affected by the Nazi occupation, and Forster (Tom Wlaschiha), Head of the Gestapo, suspects as much, as Simone and her roommate Margot (Fleur Geffrier) work to secure an escape route for a Jewish family.

Season Three
The third series follows the tense struggles of a young U-boat crew as they engage in the Battle of the Atlantic whilst being hunted down by an obsessed Royal Navy Commander in a thrilling game of cat-and-mouse. They are sent on a dangerous mission to the Southern Hemisphere under the command of Robert Ehrenberg (Franz Dinda) who finds redemption and the family bonds he thought heâ??d lost forever. The drama takes us to Northern Germanyâ??s Kiel, the major naval base of the German Reich for the first time, with each historically based strand leading to an epic series finale.