Forster is investigating the village man murder case in Lisbon. In Kiel, the new sailors of the U-949 get into battle. Royal Navy captain Swinburne is travelling to Liverpool for his son's funeral service.

Spring 1943: L.I. Ehrenberg prepares submarines for use in Kiel. Minors are recruited as crews. Wilhelm Hoffmann attends a reception at the request of his son-in-law.

The U-949 is in danger during a test drive due to Commander Buchner's orders. Forster comes across a trail in a casino and makes the acquaintance of the German Bettina Gruber.

While Swinburne sets sail with a technologically upgraded ship, Ehrenberg makes a serious decision in Kiel. Forster has to create a traitor out of the country.

After Wilhelm Hoffmann learned the truth about his son Klaus, he gets into a fight with Hannie. Ehrenberg has to say goodbye to Greta. In Portugal, Forster's plan gets out of hand.

Swinburne's destroyer sinks two submarines on the Atlantic, then he hunts U-949. Forster observes a secret meeting between consul Gruber and the American Gardiner.

After a bomb explosion, Forster and Klaus Hoffmann hide with the Portuguese Ines, while Wilhelm Hoffmann arrives in Lisbon. U-949 is heading for their new destination.

The U-949 reaches Portugal and unloads the gold. When Ehrenberg returns to Kiel, he finds Greta with her husband again. Klaus Hoffmann and Forster reach their goal through blackmail.

Klaus Hoffmann pursues the German agent Weiss and discovers valuable information. U-949 is under heavy fire from Swinburne's destroyer - until Commander Buchner dares a manoeuvre.

U-949 meets a Japanese boat to take over heavy cargo - gold. Wilhelm Hoffmann receives an invitation to Lisbon. Forster betrays Klaus Hoffmann under duress what he knows.