August 1943: Franz Buchner is in action with the U-949. An informer on board divides his crew. The Hoffmann family comes together in Berlin to attend the premiere of a film about Klaus.

Robert Ehrenberg supports the resistance within the navy and gives Klaus Hoffmann a tip. Bobby Schulz is on his trail. U-949 comes under fire in the Strait of Gibraltar.

Commander Buchner reaches the coast of Naples. Klaus Hoffmann is also on his way there. His sister Hannie meets twelve-year-old Hertha.

Klaus Hoffmann commands the dilapidated U-330 on a secret dive, but not all men trust him. Hannie wants to take Hertha in. Staff officer Heinrich Gluck has to make a decision.

Schulz kills with his own hand for the second time. Klaus Hoffmann realizes that the Allied invasion has long been underway. A man is waiting in Naples with a murder order.