December 1942: The experienced submarine commander Johannes von Reinhartz (Clemens Schick) and his crew set sail with U-822 on a secret mission. However, when the captain's loyalty is soon questioned, U-612 under the command of Ulrich Wrangel (Stefan Konarske) gives chase.

Klaus Hoffmann (Rick Okon) was able to escape death on the Atlantic. In New York he is taken in by Sam Greenwood (Vincent Kartheiser) and through him gets to know the shady lawyer Berger (Thomas Kretschmann). Can this enable him to return to Germany?

In La Rochelle, Simone (Vicky Krieps) continues to be active in the resistance, although Gestapo chief Forster (Tom Wlaschiha) has her in his sights. Together with Margot (Fleur Geffrier) she wants to help a Jewish family escape.